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					ESP (Electronic Stability Program)




                                     ESP
     (Electronic Stability Program)




                                      1    Chonan Technical Service Training Center
ESP (Electronic Stability Program)




                                           CONTENTS




 1. ESP SYSTEM (BOSCH ESP 8) --------------------------------------------------


 2. ESP CONTROL MODULE --------------------------------------------------------------


 3. BASIC FUNCTIONS OF ESP ----------------------------------------------------------


 4. HYDRAULIC CONTROL UNIT ---------------------------------------------


 5. HYDRAULIC BRAKE ASSIST (HBA) ---------------------------------------


 6. INPUTS AND OUTPUTS ----------------------------------------------------------------


 7. FAILSAFE ----------------------------------------------------------------------------------




                                                     2             Chonan Technical Service Training Center
ESP (Electronic Stability Program)

1. ESP SYSTEM (BOSCH ESP 8)

In critical situation, ESP helps you remain in control of your vehicle and thus avoid serious
accidents. ESP, the Electronic Stability Program from Bosch, by stabilizing the vehicle provides for
the active improvement of its behavior whenever a critical driving situation is encountered. ESP
incorporates the functions of both the Antilock Braking System (ABS) and the Traction Control
System (TCS) - while going much, much further with respect to its range of functions. It also
reduces the danger of skidding in all situations, and detects an incipient dangerous situation before
it actually occurs, and reacts automatically. By selectively braking individual wheels, ESP stabilizes
the vehicle and keeps it safely on track.




                          [ESP: ABS + TCS + AYC (Active Yaw Control)]

Under all operating conditions, in event of panic braking or normal braking, when the vehicle is
rolling freely or accelerating, or during trailing throttle or change of load. ESP ensures that the
vehicle remains on track and that the driver retains full control. Impending instability, or
oversteering and understeering are registered immediately. And as soon as a given situation
threatens to become problematical ESP intervenes to restore vehicle stability.

Individual braking of the wheels plays a central role in ESP. In other words, to bring the vehicle
back on the course again, a precisely metered braking pressure is applied at each wheel
completely independent of the other wheels. Furthermore, ESP can reduce engine torque and
intervene in the gearshift sequence of automatic gearboxes. To this end, ESP employs a
microcomputer whose software evaluates the signals from ESP sensors and outputs the necessary
commands.

ESP increases active safety in all driving situations. Particularly when you are cornering, in other
words when lateral forces are at work, ESP stabilizes your vehicle and keeps it safely in lane.
ABS and TCS act “only” in the longitudinal direction. ESP employs all the components of ABS/TCS.
In addition, ESP incorporates a yaw-rate sensor with integral lateral-acceleration sensor and a
steering wheel angle sensor.


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ESP (Electronic Stability Program)




                                  [Active Yaw Control of the ESP]


ESP essentially consists of three assemblies: the sensors, the electronic control unit and actuators.
Sensors measure the position of the steering wheel, the pressure in the master brake cylinder, the
yaw velocity (‘yaw rate’) and the acceleration transverse to the vehicle (lateral acceleration). This
makes it possible to compare the driver’s intention with the momentary vehicle behavior so that in
the event of interfering deviations with adverse affect on driving safety the electronic control unit
can initiate appropriate corrective action.




                                    [ESP System Components]




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ESP (Electronic Stability Program)

ESP recognizes critical driving conditions, such as panic reactions in dangerous situations, and
stabilizes the vehicle by wheel-individual braking and engine control intervention with no need for
actuating the brake or the gas pedal.
ESP adds a further function known as Active Yaw Control (AYC) to the ABS, TCS, EBD functions.
Whereas the ABS/TCS function controls wheel slip during braking and acceleration and, thus,
mainly intervenes in the longitudinal dynamics of the vehicle, active yaw control stabilizes the
vehicle about its vertical axis. This is achieved by wheel-individual brake intervention and
adaptation of the momentary engine torque with no need for any action to be taken by the driver.




                    GENERAL      MIDDLE
        SYSTEM                              EUROPE         AUS       CANADA        USA
                     AREA         EAST
           ABS          O           O           S           O           O            O
                                                                                   O
           ESP          O           O           O           O           O
                                                                                (GLS only)

         [Application of NF ABS/ESP (O: Optional Item, S: Standard Item), August 2004]




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ESP (Electronic Stability Program)

2. ESP CONTROL MODULE

This unit has the functions as follows:

 - Input of signal from Pressure sensor, Steering angle
    sensor, Yaw & Lateral acceleration sensor, Wheel
    speed sensors. The signals produced by the sensors
    are evaluated in the electronic control unit.

 - Control of braking force / traction force/ yaw moment
 - Failsafe function
 - Self diagnosis function
 - Interface with the external diagnosis tester

The signals produced by the sensors are evaluated in the electronic control unit. From the
information received, the control module must first compute the following variables:
yaw rate, longitudinal acceleration, lateral acceleration, pressure in hydraulic system, wheel speed,
reference speed, slip



Variant coding

This service enables to write the variant. Normally the variant has been calculated by the CAN
component and automatically written into EEPROM.

The ESP software changes according to the vehicle parameter. ESP receives data for variant
coding such as engine type, engine displacement and AT type via CAN. ESPCM writes the proper
variant code on the EEPROM on the base of the received data.

Variant coding must be performed after replacement of the ECM or TCM or ESPCM.




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ESP (Electronic Stability Program)

Procedure (Work instruction)

 ① Turn the ignition key on

 ② Connect a Hi-scan pro on the vehicle

 ③ Select anti-lock brake system on the menu




 ④ Select ‘Variant Coding’




 ⑤ Off the Hi scan and turn ignition off

 ⑥ Turn the ignition key on




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ESP (Electronic Stability Program)

3. BASIC FUNCTIONS OF ESP

ESP checks not only the driver’s steering inputs and compares them with the vehicle’s actual
behavior, but also whether the driver’s input and the actual direction of travel coincide, in other
words, whether the actual situation and the direction the driver wants the vehicle to take agree fully
with each other.




                                     [Concept of ESP control]

ESP reacts in a way which is far beyond the driver’s capabilities, and automatically “steers” the
vehicle back in the correct direction by selective application of brakes. In other words, ESP
ensures that the vehicle behaves in the customary manner - even in the most extreme situations.
Instead of breaking away or starting to skid, the vehicle complies with the inputs from the steering
wheel, and the driver remains in complete control.

When the wheel is steered, driving intention is detected by ESPCM as an amount of the steering
angle. By the steering angle, reference speed, acceleration/deceleration, ESPCM calculates a yaw
rate as well as a lateral G value. This result is just an expected vehicle movement by a driver.

However, the reality that happens to the vehicle is not same all the time. Real movement of the
vehicle can be detected by a yaw rate sensor and lateral G sensor. Sometimes the real movement
and the expected movement goes on different way.



  - In the event of oversteering
    If an over-steering symptom begins to start while turning, vehicle moves far inward. Then, over-
    steering control activates. When the braking force is applied to front outer wheels, yaw moment
    in opposite direction is generated to compensate the over-steer. Therefore, vehicle moves as
    the driver intends.


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ESP (Electronic Stability Program)




  [In the event of oversteering]
  If a swerving tail end shows that the car is in danger of
  oversteering, the front wheel on the outside of the bend is
  braked. The compensating yawing moment, which now acts
  in the clockwise direction, turns the car back into the desired
  direction.




  - In the event of understeering
    When an under-steering symptom begins while the vehicle turning, vehicle slips outward
    regardless of driver’s intention. Then, under-steering control starts. The control module
    generates the braking force at the inner side of the rear wheel and yaw moment generates, in
    which vehicle tries to turn to inner side of the road. In this case, the greater force is introduced
    via the rear wheel so that the lateral force is selectively reduced in exact does to stabilize the
    vehicle.




  [In the event of understeering]
  If the car is understeered with the front wheels pushing
  outward, a compensating yawing moment which returns the
  car body to the desired curse is built up by braking the rear
  wheel on the inside of the bend.


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ESP (Electronic Stability Program)

For example, if the expected yaw rate is 20 deg/sec and the yaw rate sensor output is only 10
deg/sec, this means that the movement of the vehicle is not steered as much as the driver
intended resulting in understeering. When the understeering symptom is detected, hydraulic
pressure is generated by the ESP motor and delivered to the rear wheel inner side to increase yaw
moment while at the same time reducing engine torque.

On the contrary, the yaw rate sensor output is bigger than the expected yaw rate, this means that
the movement of the vehicle is turning more than the driver intended resulting in oversteering.
When the oversteering is detected, hydraulic pressure is delivered to the front outside wheel to
decrease yaw moment.




                             [ESP control pattern (Sample)]




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ESP (Electronic Stability Program)

4. HYDRAULIC CONTROL UNIT



                                                            Solenoid Valve (x12)


                                                                    Valve Coil (x12)




      Motor



     Pump (x2)


     Low Pressure Chamber
          Piston (x2)
                                                                                ESPCM
                    Pressure Sensor



In the hydraulic control unit of the Bosch ESP8,

 -   Motor & Pumps (2EA)
 -   Low Pressure Accumulator (2EA)
 -   Solenoid valves (12EA)
 -   Pressure sensor

One thing particular regarding the construction of
Bosch ESP8, is that pressure sensor is located
inside HCU. In case of Mando MGH-25 ESP of
Tucson, the pressure sensor is positioned on the
master cylinder.




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ESP (Electronic Stability Program)

 4.1 HYDRAULIC CIRCUIT (BOSCH ESP8)




  - Inlet solenoid valve (EV)
    This valve connects or disconnects the hydraulic path between master cylinder and the wheel
    cylinders. It remains open normally but it is closed when the dump and hold mode begins
    during ABS operation. Check valve is to help the brake fluid returning from the wheel cylinder to
    the master cylinder when the brake pedal is released.

  - Outlet solenoid valve (AV)
    This valve is normally closed but it is opened to release the wheel cylinder pressure when a
    dump mode begins.

  - Electric shuttle valve (HSV)
     When the ESP is in operation, the brake fluid should be supplied to the motor pump from the
     M/C via the shuttle valve to generate the brake pressure. This solenoid valve is closed and
     blocks the passage when a brake pedal is applied.

  - Traction control valve (USV)
     In case of a normal condition, this valve remains open and the brake pressure from the M/C
     can be applied to the front wheel via TC valve. While the TCS or ESP in operation, TC valve is
     closed and the generated pressure by motor delivers to wheel cylinders without returning to
     the master cylinder.




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ESP (Electronic Stability Program)

    TC valve includes a relief valve and a check valve. When excessive pressure is supplied from
    the motor, relief valve is opened and the pressure is relieved.


  - Pressure sensor (UP)
     It monitors brake pressure of the brake line. This sensor signal is the basic data for hydraulic
     brake assistance control.




 4.2 HYDRAULIC FLOW (ESP8)


   - In braking mode
     In this position, inlet valve (EV) and TCS valve (USV) are open, outlet valve (AV) and the
     electrically operated shuttle valve (HSV) remain closed.




                                      [Oil flow while braking]




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ESP (Electronic Stability Program)

   - In ESP control (pressure increase)
     In this position, the inlet valve (EV) is driven in a pulsed cycle. The TCS valve (USV) is almost
     closed (PWM control). The outlet valve (AV) remains closed. The electrically operated shuttle
     valve (HSV) is opened. The motor speed is in a MSC (Motor Speed Control).




   - In ESP control (pressure dump)
     In this position, the inlet valve (EV) is closed and the outlet valve (AV) remains open.
     The TCS valve (USV) is partially open and the electrically operated shuttle valve (HSV) is
     opened. The motor speed is in a low MSC (Motor Speed Control).




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ESP (Electronic Stability Program)

 4.3 AIR BLEEDING IN THE WORKSHOP LOCATION



  1) Normal air-bleeding




The brake fluid passes into the reservoir and is pushed by the admission pressure of the bleeding /
filling unit through the brake master cylinder (MC1, MC2) and through the hydraulic unit into the
wheel brake cylinder.
The bleed screw of this brake cylinder is open (figure above shows front left LF). All other bleed
screws are closed. During bleeding of the primary circuit, the pedal can be actuated to assist the
admission pressure and thereby improve the result. The duration of primary bleeding depends on
the bleeding process. The main factor is that the wheel must be bled until bubble and foam-free
brake fluid can be clearly seen emerging. Repeat the same bleeding procedure on the remaining 3
wheels.




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ESP (Electronic Stability Program)

 2) Secondary circuit bleeding

  Only to be carried out if a definite diagnosis can be made of “soft brake pedal” or “excessive
  pedal travel” following operation of ABS, ESP or solenoid valve actuation.

  To carry out this method of bleeding, a tester with the specifically developed bleeding routines,
  which must be implemented in the tester is required. To increase the pressure in the outlet valve
  and pump channels (bypass channels), the brake pedal is to be actuated during flushing (pulses).



  Procedure

  ① Make Hi-scan pro for serial diagnosis available.




  ② Make bleeding / filling unit and reservoir bottle available.

  ③ The sequence of bleeding is not important. It is however specified that all 4 wheel circuits
    must be bled at least once.

  ④ Bleed channels until routine is complete. Routine should not be prematurely interrupted.

  ⑤ On completion of routine, bubble-free brake fluid must emerge. If necessary, repeat routine.

  ⑥ While routine is in progress, brake pedal assistance is required to increase the pressure.




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ESP (Electronic Stability Program)

   - Diagonal brake circuit layout (ABS8)

    The bleed screw of LF wheel is opened. Fluid flows via the inlet valve (EVLF of the primary
    circuit) to wheel connection (LF. All other bleed screws are closed).

    The Hi-scan pro switches the pump on and pulses the outlet valves (AVRR and AVLF)
    literately from brake master cylinder circuit. Due to the restriction in the inlet valve, a pressure
    drop occurs in the pump circuit and the brake fluid enters the opposite wheel circuit. Actuating
    the brake master cylinder produces a pressure peak, which pushes the brake fluid through the
    outlet valve to the pump. The pump is supplied and pushes the fluid against the admission
    pressure to the open bleed screw.

    Consequently, the opposite outlet valve must alternately be pulsed, if the secondary circuit of a
    wheel is to be bled. Because of differing brake circuit layouts, the valve selection must
    correspond to the layout. The time for secondary circuit bleeding is determined by the Hi-scan
    pro. The brake pedal must be continually actuated during secondary circuit bleeding.




          [ABS8 Hydraulic diagram as example for secondary circuit bleeding on wheel LF]



  - Diagonal brake circuit layout (ESP8)

   Bleeding takes place over 2 phases. Firstly as on ABS the bleed screw of LF wheel is opened.
   Fluid flows via the USV1 and the inlet vale (EVLF) of the primary circuit to wheel connection
   (LF). All other screws are closed.


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ESP (Electronic Stability Program)

   Phase 1 (dark line), starts with the same actuation as described for ABS. the Hi-scan pro
   switches the pump on and pulses the outlet valves (AVRR) and (AVLF) alternately from brake
   master cylinder circuit. Due to the restriction in the inlet valve, a pressure drop occurs in the
   pump circuit and the brake fluid enters the opposite wheel circuit. Actuating the brake master
   cylinder produces a pressure peak, which pushes the brake fluid through the outlet valve to the
   pump. The pump is supplied and pushes the fluid against the admission pressure to the open
   bleed screw.

   Phase 2 (light line), bleeding of the ESP circuits follows, which could also be described as
   suction circuit bleeding. The bleed screw remains open. The Hi-scan pro now pulses the
   suction valve (HSV1) and allows the pump motor to run. During actuation of the brake master
   cylinder a pressure peak is produced, which pushes the fluid through the suction valve to the
   pump. The pump is supplied and pushes the fluid via the inlet valve (EVLF) to the open bleed
   screw. Because of differing brake circuit layouts, the valve selection must correspond to the
   layout. The time for secondary circuit bleeding is determined by the Hi-scan pro. The brake
   pedal must be continually actuated during secondary circuit bleeding.




       [ESP Hydraulic diagram with diagonal brake circuit layout as example for secondary
       circuit bleeding on wheel LF]



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ESP (Electronic Stability Program)

5. HYDRAULIC BRAKE ASSIST (HBA)

The major feature of the hydraulic brake assist (HBA) is the detection of an emergency brake
situation and so caused automatic increase of the vehicle deceleration. The vehicle deceleration is
only limited by the ABS control and therefore the vehicle deceleration is at its physical limitation.
Thus a usual driver can now reach a stopping distance as short as a well trained driver
Reduces the driver his brake demand the vehicle deceleration will be reduced proportional to the
brake pedal force. So the driver may exactly adjust the deceleration after an eventual clarification
of the emergency situation.




The graph shows the reaction of drivers at panic stop. Dot line (1) and (2) in the graph means that
woman, the old or inexperienced driver cannot generate enough pressure to operate ABS during
panic braking. The main job of the HBA is to build up the pressure enough to operate ABS in the
emergency braking situation.




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ESP (Electronic Stability Program)

Design
The HBA has the function to generate brake pressure by using the ESP unit without additional
parts. The hydraulic brake assist system is based on the ESP components. The function of the
HBA is integrated in the software of the ESP control unit.


Operating condition
ESP control module monitors the brake pedal applied speed by monitoring the pressure increase
rate of the pressure sensors inside the hydraulic control unit. While HBA operation, ESP control
module operates the motor and increase brake pressure rapidly to obtain the maximum brake force.
To operate BAS, following 3 conditions should be met simultaneously.

Braking pressure should exceed 30 bar, pressure increase rate is more than 2200 bar/sec and the
vehicle speed exceeds 20 km/h.




                       - over 30 bar
                       - over 2200 bar/sec
                       - over 20 km/h




Control flow logic


                                                  Detect emergency
    Emergency condition occurs
                                                (M/C pressure sensor)



                             Increase brake pressure                    Execute an emergency
                            until the wheel slip occurs                  decision logic (ECU)



     Execute the ABS control logic




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ESP (Electronic Stability Program)


6. INPUTS AND OUTPUTS




   Pressure Sensor
   (HCU Built-in type)




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ESP (Electronic Stability Program)

  1) ACTIVE WHEEL SPEED SENSOR


a. Features

     - Type: Active Type (Hall IC type)

     - Components: HALL IC, Capacitor, Magnet

     - Output signal: Digital (Open Collector Type
       circuit integrated)

     - Good characteristics     against      temperature
       variation and noise

     - Low RPM Detection: 0 RPM can be detected

     - Air gap sensitivity: stable output pulse width
       against air-gap change

     - Supplying power: DC 12V


b. Specification

                OUTPUT SIGNAL                    MAX          TYPICAL      MIN

         LOWER SIGNAL         ILOW (mA)          5.9            7          8.4

         UPPER SIGNAL         IHIGH (mA)         11.8           14         16.8

         SIGNAL RATIO         IHIGH / ILOW      1.85 or more

         OPERATING FREQUENCY                    1 ~ 2500 Hz

         OPERATING DUTY                         30~70%



c. Operation

   Generated output current from the sensor is 7mA or 14mA.
   So in order to check the sensor function, the output current
   needs to be checked. If the current measurement is not
   available, the output voltage waveform can be checked.

   The wheel sensors are constantly checked electrically by
   the control module. In addition, the sensor signal is
   checked while the vehicle is running. If there is a
   malfunction or a non-plausible physically possible signal,
   ABS and ESP is switched off and the ABS warning lamp

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ESP (Electronic Stability Program)

   and ESP OFF warning lamp is switched on.




                                 a


                                          b


                          [Principle of Active Wheel Speed Sensor]
   a : High signal (Signal A - Signal B > 0), b : Low signal (Signal A - Signal B < 0)



   Comparison between the passive wheel sensor and the active wheel sensor


         Item                    Passive sensor                              Active sensor

      Sensor Size                       Larger                                   Smaller
                                                                      (possibly smaller by 40~50%)

       One Chip                       Impossible                                  Good

    Mass production                    Medium                                     Good


      Zero Speed      Cannot be detected at low speed ( 3km/h                 Nearly 0 KPH
                                     or less)                               (Intelligent Type)

         Temp.                       -40 ~ +125 ℃                            -40 ~ +150 ℃

        Air-gap              Sensitive (Vout∝ 1/(gap)2)                  Dull (frequency change)
       Sensitivity                 Max.: 1.3mm                                 Max.: 3.0mm


       Anti-noise                       Poor                                      Good




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ESP (Electronic Stability Program)

  2) YAW RATE SENSOR & LATERAL ACCELERATION SENSOR

  The purpose of the Yaw Rate Sensor is to measure the
  physical effects of yawing and lateral acceleration. If mounted
  appropriately, the sensor is measuring the yaw rate and
  lateral acceleration of the vehicle. In order to achieve this, the
  sensor features both a measuring element for yaw rate and
  one for acceleration, with one appropriate integrated circuit.

  The yaw rate sensing element and an additional micro-
  machined element sensing the acceleration normal to the
  driving direction are located on a ceramic hybrid inside the
  metal module. The yaw rate sensor is based on the detection
  of a coriolis force normal to two out-of-phase oscillating
  seismic masses.

  Output signals comprise simultaneously the yaw rate and the
  linear acceleration normal to the driving direction. The yaw
  rate output signal is superimposed by an internally generated
  reference voltage of 2.5V.

   Apart from the measuring element for yaw rate, a micro-
  machined element for acceleration is utilized to measure the
  vehicle’s lateral acceleration. Its principle is also based on
  capacitive detection.



    a. General Specification (Electrical)
       -   Operating temperature        :   - 40 ~ + 85 °C
       -   Supply voltage              :    8 V ~ 16 V
       -   Nominal voltage             :    12 V nominal
       -   Current consumption at 12V :     80 mA
       -   Pin layout




                  [Sensor connector]




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ESP (Electronic Stability Program)

   b. Yaw Rate Sensor Specification
      - Measuring Range           : ±100˚/s
      - Resolution               :  0.3˚/s
      - Output Voltage Range : 0.5 ~ 4.5V
      - Sensitivity          : 18 mV / (°/s)


   c. Lateral G (Acceleration) Sensor Specification
      - Measuring Range            : ±1.8 g (±1.5G)
      - Resolution                :  0,005 g
      - Output Voltage Range : 0.5 ~ 4.5 V
      - Sensitivity          : 1V/g


   d. Input-Output Characteristics Yaw Rate Sensor & Lateral Acceleration Sensor




    [Yaw rate output]                                      [Acceleration output]
    Driving through a left turn leads to a positive        Driving through a left turn leads to an
    yaw rate ω, this leads to a positive output            acceleration in the -y direction, this leads to a
    voltage (Differentially measured against               positive output voltage (differentially measured
    Reference Output).                                     against Reference Output).




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   e. Hi-scan Current Data




                                                        Output of Bite terminal




               Yaw rate output                       Lateral acceleration output




        [Yaw rate output & Bite output         [Lateral acceleration output & Bite
        when the ignition is turned on]        output when the ignition is turned on]




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   f.   Operating Principle
        Oscillating masses suspended by springs are oscillating along the direction indicated by the
        green arrows. A yaw rate  applied normal to the sensor-plane generates a coriolis force on
        the acceleration elements. The comb-like structure moves and therefore it is changing its
        capacity along the direction of sensitivity. The capacitor change is detected by the electronic
        circuit. The difference signal of the two capacitors is directly proportional to the acting yaw
        rate.




   g. Caution
        The sensor is very sensitive to shock acceleration on its casing and on the sensor element.
        Stimulation by impacts as hammer blows in the course of bodywork repairs is not
        permissible. Before such operations, the sensor must be removed from the bodywork.
        Furthermore the sensor must not be dropped or struck hard. If such events do occurs,
        before fitting the sensor it must be checked that it is functioning correctly.




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ESP (Electronic Stability Program)

3) STEERING ANGLE SENSOR
 Steering angle sensor developed by Bosch is quite a
 different from the photo interrupt type which is well
 known to us. The steering angle sensor signal is
 scanned via CAN-Bus by the ESP control unit. According
 to the position of steering wheel, the allocation of the
 steering angle sensor signal and can be checked via the
 diagnosis function.

 The features are followed.

 - Contactless principle
 - AMR (Anisotropic Magneto Resistive effect) technology
 - Absolute measuring of steering wheel angle
 - Output of steering angle velocity
 - Calibration of zero position via CAN interface
 - Continuous self test
 - Variable design applications available
                                                                                 [Location]

 a. General Specification

   - Supply voltage                    : 8 V ~ 16 V

   - Nominal voltage                   : 12 V

   - Measuring Range                   :   - 780 ~ -779.9 ˚ (Angle),   0 ~ 1016 ˚/s (Velocity)

   - Resolution                        :   0.1 ˚ (Angle) , 4 ˚/s (Velocity)

   - Recurrence of zero point          :   -2.5 ˚ ~ +2.5˚
     (Switch on to switch on again)

   - Variation of zero point         : -5 ˚ ~ +5˚
     (Max. tolerance of zero point between mechanical interface of the sensor and measurement
     signal)




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ESP (Electronic Stability Program)

   b. Operating Principle
      A non contact, analog angle sensor is
      carrying out absolute measuring by the use
      of the Anisotropic-Magneto-Resistive effect
      (AMR).
      Absolute angle is measured by means of a
      toothed gear with magnetic properties in
      combination with different ratios.
      Corresponding AMR elements that change
      their electrical resistance according to the
      magnetic field direction detect the angle
      position of the measuring gears. A micro-
      controller decodes the measured voltage
      signals after A/D converting with the help of
      a mathematical function. Output of the digital
      angle value and velocity is sent to the
      ESPCM via CAN-interface.                                      [Construction]




      There are three measuring gears (θ, ψ, φ) inside the sensor. The two of measuring
      gearwheels with different number of teeth have magnets inside. Rotating angle of each
      measuring gearwheel is detected by AMR elements and the difference of angle between
      the two gears is getting increased as the hub gearwheel rotates. So the steering angle (φ)
      can be calculated from the angular difference of θ and ψ.




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ESP (Electronic Stability Program)

   c. Hi-scan Current Data




   d. Steering Angle Calibration
      When steering wheel angle sensor has been replaced, the new one must be newly
      calibrated after fitting. Steering must be in serviceable condition before calibration. The toe
      for straight-ahead position is determined with the aid of a suspension analysis, which forms
      the status for a correct calibration (output of 0 corresponds with straight-ahead position).
      This also applies if repair work is being carried out on the steering, or the sensor has been
      removed. However, calibration is not required after replacement of control unit, or after
      repairs to the vehicle wiring of after a fault in the supply voltage.

      Effects when sensor is not calibrated:
      A de-calibrated sensor is recognized immediately after turning on the ignition, the ESP
      warning lamp lit on and a fault code is registered in the control unit. If however a previously
      calibrated sensor is fitted to the vehicle and the new calibration is not carried out, then the
      output of 0 will probably not correspond with the straight-ahead position. The system
      recognizes this condition after a short driving distance, does not however switch off when
      the sensor supplies valid values of up to +/- 15˚ in straight-ahead position. In this case the
      new zero position will be learned via the permanent long-term adjustment. After a journey
      of approximately 6 km, without interruption in the ignition and with frequent straight-ahead
      driving, the deviation is reduced to approximately 50% (reduction cannot be observed with
      serial tester, as correction is carried out in control unit). If the straight-ahead position and 0˚
      is a poor match, then ESP control can be rather uncomfortable until new zero position is
      fully learned.




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ESP (Electronic Stability Program)

      Procedure (Work instruction)

       ① Suspension analysis for steering angle calibration or wheel in straight-ahead position.
         A prolonged straight-ahead drive can also be used during calibration to determine the
         steering wheel center position.

       ② Calibration of the wheel angle sensor in straight-ahead position

           - The steering wheel position for the calibration of
             the steering angle sensor must be    in a straight
             position. The maximum allowed tolerance for the
             calibration amounts ± 5º. Only possible when
             sum tolerance isn’t deviated.

           - Threshold for system limit shut off by > 15 º

           - The verification checks the programmed code by
             reading and evaluating of the input & output data.

           - An incorrect calibration will set a fault code in the
             fault code memory. To verify a not OK calibration
             it is necessary to make an ignition cycle. The
             calibration will be initiated after the next ignition
             cycle.

       ③ Connect a Hi-scan pro on the vehicle.

       ④ Select the ‘Anti-lock brake system’ on the menu.




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ESP (Electronic Stability Program)

       ⑤ Select ‘SAS Calibration’.




       ⑥ Perform the ‘SAS Calibration’.




       ⑦ Turn off the Hi-scan pro.

       ⑧ Verification the programmed code (calibration) by reading and evaluation the input &
         output data.




                                            32           Chonan Technical Service Training Center
ESP (Electronic Stability Program)

4) PRESSURE SENSOR

 Pressure sensor detects the master cylinder pressure.
 The sensor information is used for HBA (Hydraulic
 Brake Assist System) control. The location is inside the
 ESP unit (HECU).

 The pressure sensor signal is scanned by the ESP
 control unit. According to the position of brake pedal,
 the allocation of the pressure sensor signal and can be
 checked via the diagnosis function.

 The pressure sensor is incorporated in the Hydraulic Unit (HU) and cannot be exchanged. The
 output of the sensor is within the HU and thus not accessible at the main connector harness of
 the ESPCM. Consequently the voltage cannot be measured with a multimeter.

 A pressure sensor fault can also be caused by a fault in the BLS circuit. Because of the logical
 link to the BLS signal during the sensor test, a fault in the BLS circuit can be logged as a
 pressure sensor fault.



  a. Specification

  - Operating Voltage    :   5± 0.25 V
  - Output voltage       : 10% Vpwr ~ 90% Vpwr
  - Operating Pressure : 0 ~ 200 bar
  - Response time        : Max.    10msec
  - Operational Temp.    : - 40℃ ~ 125 ℃


  b. Hi-scan Current Data




                                              33            Chonan Technical Service Training Center
ESP (Electronic Stability Program)

5) ESP SWITCH

 The ESP switch deactivates the ESP and TCS functions. It is located on the dashboard of driver
 side. The system is generally active after each new start and is only deactivated by actuating the
 ESP switch.

 The switch status is scanned by the control unit. According to the position of the switch, the
 allocation of the switch position and of the wiring can be checked via the diagnosis function.

  • This facilitates

   - rocking to free the vehicle in deep snow or loose surface material

   - driving with snow chains

   - operation of the vehicle on a brake test bench

  • The ABS function is fully maintained.



6) WARNING LAMP CONTROL



                                                                              b)

                                                                   d) c)




             a)



     a) EBD warning lamp control                    b) ABS warning lamp control
     c) TCS/ESP OFF warning lamp control            d) TCS/ESP function lamp control



 a) EBD warning lamp control
  The active EBD warning lamp module indicates the self-test and failure status of the EBD.
  However, in case the Parking Brake Switch is turned on, the EBD warning lamp is always turned
  on regardless of EBD functions.
  The EBD warning lamp shall be on:
   - During the initialization phase after IGN ON. (continuously 3 seconds)

                                               34            Chonan Technical Service Training Center
ESP (Electronic Stability Program)

   - When the Parking Brake Switch is ON or brake fluid level is low
   - When the EBD function is out of order
   - During diagnostic mode
   - When the ECU Connector is separated from ECU.


 b) ABS warning lamp control
  The active ABS warning lamp module indicates the self-test and failure status of the ABS.
  The ABS warning lamp shall be on:
   - During the initialization phase after IGN ON. (continuously 3 seconds)
   - In the event of inhibition of ABS functions by failure
   - During diagnostic mode
   - When the ECU Connector is separated from ECU.


 c) TCS/ESP OFF warning lamp control
  The TCS/ ESP warning lamp indicates the self-test and failure status of the TCS/ESP. The TCS/
  ESP warning lamp is turned on under the following conditions:
   - Ring the initialization phase after IGN ON. (continuously 3 seconds)
   - In the event of inhibition of TCS/ESP functions by failure
   - When driver turns off the TCS/ESP function by on/off switch
   - During diagnostic mode


 d) TCS/ESP function lamp control
 The TCS/ESP function lamp indicates the self-test and operating status of the TCS/ESP. The
 ESP warning lamp lights up briefly when the ignition is turned on and is extinguished as soon as
 the peripherals have been checked. During an ESP/TCS control cycle, the ESP function lamp
 flashes to show the driver that the system is active and that the vehicle is at the limit of its
 physical capabilities. Detection of the fault in the ESP system causes the ESP warning lamp to
 light up and remain on. The ESP system is then inactive, the ABS function is fully maintained.
 The TCS/ ESP Function lamp operates under the following conditions :
   - During the initialization phase after IGN ON. (continuously 3 seconds)
   - When the TCS/ESP control is operating. (Blinking - 2Hz)




                                                 35           Chonan Technical Service Training Center
ESP (Electronic Stability Program)

7. FAILSAFE


 1) ABS/EBD Keep Alive and Shutdown Matrix


                                        Driving Condition during Failure
                                                  Detection
                          EBD keep                                           Warning Lamp
        Failure                                            Decelleration,
                            alive       Out of Control
                                                            In Control
                                          ABS, EBD          ABS, EBD          EBD       ABS
 ECU hardware error           X                X                 X              X        X
 Over-voltage fault           X                X                 X              X        X
 Under-voltage fault          O                X                 X              O        X
 WSS_FL                       O                X                 E              O        X
 WSS_FR                       O                X                 E              O        X
 WSS_RL                       O                X                 E              O        X
 WSS_RR                       O                X                 E              O        X
 WSS GENERIC                  X                X                 X              X        X
 WSS voltage                  O                X                 X              O        X
 FL outlet valve              X                X                 X              X        X
 FL inlet valve               X                X                 X              X        X
 FR outlet valve              X                X                 X              X        X
 FR inlet valve               X                X                 X              X        X
 RL outlet valve              X                X                 X              X        X
 RL inlet valve               X                X                 X              X        X
 RR outlet valve              X                X                 X              X        X
 RR inlet valve               X                X                 X              X        X
 Motor pump                   O                X                 X              X        X
 BLS                          O                O                 O              O        O
 Valve relay                  X                X                 X              X        X
 X : Immediate system stop and warning lamp on
 E : System stop after system control
 O : System operation, No warning lamp
 ※ 1~2 wheel sensor failure: EBD keep alive function, 3 or more sensor failure: EBD control stop


                                             36            Chonan Technical Service Training Center
ESP (Electronic Stability Program)

 2) DTC Table

                                                                 ACTIVE COMPONENTS          WARNING LAMP
    DTC                         NAME
                                                           EBD   ABS ETC* BTC* ESP HBA* EBD      ABS   ESP

   C1101    ECU High Voltage                                -     -     -     -    -   -    ●     ●    ●

   C1102    ECU Low Voltage                                ka     -     -     -    -   -     -    ●    ●

   C1200    WSS FL Open or Short                           ●     rc     -     -    -   -     -    ●    ●

   C1201    WSS FL Range, Performance, Intermittant        ●     rc     -     -    -   -     -    ●    ●

   C1202    WSS FL Invalid/No singal                       ●     rc     -     -    -   -     -    ●    ●

   C1203    WSS FR Open or Short                           ●     rc     -     -    -   -     -    ●    ●

   C1204    WSS FR Range, Performance, Intermittant        ●     rc     -     -    -   -     -    ●    ●

   C1205    WSS FR Invalid/No singal                       ●     rc     -     -    -   -     -    ●    ●

   C1206    WSS RL Open or Short                           ●     rc     -     -    -   -     -    ●    ●

   C1207    WSS RL Range, Performance, Intermittant        ●     rc     -     -    -   -     -    ●    ●

   C1208    WSS RL Invalid/No singal                       ●     rc     -     -    -   -     -    ●    ●

   C1209    WSS RR Open or Short                           ●     rc     -     -    -   -     -    ●    ●

   C1210    WSS RR Range, Performance, Intermittant        ●     rc     -     -    -   -     -    ●    ●

   C1211    WSS RR Invalid/No singal                       ●     rc     -     -    -   -     -    ●    ●

   C1213    Wheel Speed Frequency Error                    ●     rc     -     -    -   -     -    ●    ●

   C1235    Pressure Sensor - Electrical                   ka    nnc   nnc   nnc   -   -     -   Ce    ●

   C1237    Pressure Sensor - Other                        ka    nnc   nnc   nnc   -   -     -   Ce    ●

   C1260    Steering Angle Sensor - signal                 ●     ka    nnc   nnc   -   -     -    -    ●

   C1261    Steering Angle Sensor not calibrated           ●     ka    nnc   nnc   -   -     -    -    ●

            Lateral G Sensor - Electrical                  ●     ka    nnc   nnc   -   -     -    -    ●
   C1282
            Yaw Rate Sensor - Electrical                   ●     ka    nnc   nnc   -   -     -    -    ●

            Lateral G Sensor - Signal                      ●     ka    nnc   nnc   -   -     -    -    ●
   C1283
            Yaw Rate Sensor - Signal                       ●     ka    nnc   nnc   -   -     -    -    ●

   C2402    Return Pump Fault (Motor Electrical)           ka     -     -     -    -   -    ●     ●    ●

   C2112    Valve Relay Error                               -     -     -     -    -   -    ●     ●    ●

   C1503    TCS/ESP switch error                           ●     ●     ●     ●     ●   ●     -    -     -
            Brake Light Switch (BLS) Error
   C1513                                                   ●     ka    nnc    -    -   -     -    -    ●
            Plausibility Error BLS vs. Pressure Sensor
   C1604    ECU Hardware Error                              -     -     -     -    -   -    ●     ●    ●

   C1605    CAN Hareware Error ABS/ESP                     ●     ka     -     -    -   -     -    -    ●

   C1611    CAN timeout EMS                                ●     ka     -     -    -   -     -    -    ●

   C1612    CAN timeout TCU                                ●     ka     -     -    -   -     -    -    ●

   C1616    CAN bus off ABS/ESP                            ●     ka     -     -    -   -     -    -    ●




                                                      37           Chonan Technical Service Training Center
ESP (Electronic Stability Program)


                                                                             ACTIVE COMPONENTS                 WARNING LAMP
      DTC                                 NAME
                                                                      EBD    ABS ETC* BTC* ESP HBA* EBD              ABS   ESP

    C1626          Implausible Control                                 ka     -      -      -     -      -      -     ●       ●

    C1623          CAN timeout SAS (Steering Angle Sensor)             ●      ka     -      -     -      -      -     -       ●

    C1625          CAN timeout ESP                                     ●      ka     -      -     -      -      -     -       ●

    C2308          FL Inlet Valve Error                                 -     -      -      -     -      -     ●      ●       ●

    C2312          FL Outlet Vavle Error                                -     -      -      -     -      -     ●      ●       ●

    C2316          FR Inlet Valve Error                                 -     -      -      -     -      -     ●      ●       ●

    C2320          FR Outlet Vavle Error                                -     -      -      -     -      -     ●      ●       ●

    C2324          RL Inlet Valve Error                                 -     -      -      -     -      -     ●      ●       ●

    C2328          RL Outlet Vavle Error                                -     -      -      -     -      -     ●      ●       ●

    C2332          RR Inlet Valve Error                                 -     -      -      -     -      -     ●      ●       ●

    C2336          RR Outlet Vavle Error                                -     -      -      -     -      -     ●      ●       ●

    C2366          USV1 Error                                           -     -      -      -     -      -     ●      ●       ●

    C2370          USV2 Error                                           -     -      -      -     -      -     ●      ●       ●

    C2372          HSV1 Error                                           -     -      -      -     -      -     ●      ●       ●

    C2374          HSV2 Error                                           -     -      -      -     -      -     ●      ●       ●

    C1702          Variant Coding Error                                 -     -      -      -     -      -     ●      ●       ●

  Ge n e r a l a bbr e via tion s :
      HBA       Hydraulic Brake Assist
      BTC       Brake Torque Control
      ETC       Engine Torque Control


  Con tr olle r a va ila bility :
       -        the respective controller is shut off at once.
       ●        full controller functionality available
                no new control: If the respective component is active, control will be finished with full performance. This
      nnc       component will be shut off after end of control. If the respective component is inactive, it is shut off
                immediately.

                reduced control: If the respective component is active, control will be finished with reduced performance.
       rc       This component will be shut off after end of control. If the respective component is inactive, it is shut off
                immediately.

                keep alive: The respective components is switched into degraded mode. Control with reduced performance
       ka
                is still possible.



  La mp a c tiva tion
       -        Lamp is switched off immediately
       ●        Lamp is switched on immediately
      Ce        Lamp is switched on at end of control




                                                                 38            Chonan Technical Service Training Center
ESP (Electronic Stability Program)

 3) Input & Output Signals

 - ABS8


                                          INPUT & OUTPUT SIGNALS
 NO       ITEM       CONDITION                                               MEASUREMENT
                                         TYPE            LEVEL/FREQ.

  1    GND           ALWAYS                          GND LEVEL

  4    GND           ALWAYS                          GND LEVEL

  2    Vb MOTOR      ALWAYS            POWER         BATT. VOLTAGE

  3    Vb VALVE      ALWAYS            POWER         BATT. VOLTAGE

 16    WP FL         IG.ON             POWER         BATT. VOLTAGE            V

                                        High : 11.8~16.8mA * 75Ω              High : V

  5    WS FL         RUNNING                                                  Low : V

                                        Low : 5.9~8.4mA * 75Ω

  9    WP FR         IG.ON             POWER         BATT. VOLTAGE            V

                                        High : 11.8~16.8mA * 75Ω              High :V

 10    WS FR         RUNNING                                                  Low :V

                                        Low : 5.9~8.4mA * 75Ω

  6    WP RL         IG.ON             POWER         BATT. VOLTAGE            V

                                        High : 11.8~16.8mA * 75Ω              High : V

 17    WS RL         RUNNING                                                  Low : V

                                        Low : 5.9~8.4mA * 75Ω

  8    WP RR         IG.ON             POWER         BATT. VOLTAGE            V

                                        High : 11.8~16.8mA * 75Ω              High : V

 19    WS RR         RUNNING                                                  Low : V

                                        Low : 5.9~8.4mA * 75Ω

                     HI-SCAN         High : 0.8*IGN Voltage or more           High : V
 11    DIAG'K'
                     DIAGNOSIS       Low : 0.2*IGN Voltage or less            Low : mV

                     KEY ON                                                   IGN ON : V
 18    IG.KEY                        BATT. VOLTAGE
                     KEY OFF                                                  IDLE : V

       BRAKE         BRAKE ON        High : 0.8*IGN Voltage or more           High : V
 20    LIGHT
       SWITCH        BRAKE OFF       Low : 0.3*IGN Voltage or less            Low : mV




                                                39           Chonan Technical Service Training Center
ESP (Electronic Stability Program)

 - ESP8

                                                     INPUT & OUTPUT SIGNALS
 No               ITEM          CONDITION                                            MEASUREMENT
                                                   TYPE            LEVEL/FREQ.

  1    GND                      ALWAYS                          GND LEVEL

  4    GND                      ALWAYS                          GND LEVEL

  2    Vb Motor                 ALWAYS            POWER         BATT. VOLTAGE

  3    Vb Valve                 ALWAYS            POWER         BATT. VOLTAGE

 26    WP FL                    IG.ON             POWER         BATT. VOLTAGE         V

                                                  High : 11.8~16.8mA *75Ω             High : V

  5    WS FL                    RUNNING                                               Low : V

                                                  Low : 5.9~8.4mA *75Ω

  9    WP FR                    IG.ON             POWER         BATT. VOLTAGE         V

                                                  High : 11.8~16.8mA *75Ω             High :V

 10    WS FR                    RUNNING                                               Low :V

                                                  Low : 5.9~8.4mA *75Ω

  6    WP RL                    IG.ON             POWER         BATT. VOLTAGE         V

                                                  High : 11.8~16.8mA *75Ω             High : V

 27    WS RL                    RUNNING                                               Low : V

                                                  Low : 5.9~8.4mA *75Ω

  8    WP RR                    IG.ON             POWER         BATT. VOLTAGE         V

                                                  High : 11.8~16.8mA *75Ω             High : V

 29    WS RR                    RUNNING                                               Low : V

                                                  Low : 5.9~8.4mA *75Ω

                                HI-SCAN           High : 0.8*IGN Voltage or more      High : V
 11    DIAG'K'
                                DIAGNOSIS         Low : 0.2*IGN Voltage or less       Low : V

                                KEY ON                                                IGN ON : V
 28    IG.KEY                                     BATT. VOLTAGE
                                KEY OFF                                               IDLE : V

                                Switch ON         High : 0.6*IGN Voltage or more      High : V
 31    ESP Passive Switch
                                Switch OFF        Low : 0.4*IGN Voltage or less       Low : V

                                Switch ON         High : 0.7*IGN Voltage or more      High : V
 36    Handbrake Switch
                                Switch OFF        Low : 0.3*IGN Voltage or less       Low : V




                                             40               Chonan Technical Service Training Center
ESP (Electronic Stability Program)


                                                        INPUT & OUTPUT SIGNALS
 No               ITEM              CONDITION                                             MEASUREMENT
                                                      TYPE            LEVEL/FREQ.

                                                        High : 4.1V or more               High : V

 37    Yaw Rate Sensor Test         IG.ON                                                 Low : V

                                                        Low : 1V or less


 18    Yaw Rate Sensor Reference    IG.ON            2.464V~2.536V                        V


                                                     Offset Voltage : 2.5V
 16    Yaw Rate Sensor Signal       IG.ON                                                 V
                                                     Ragne : 0.35V~4.65V (-100~100 ˚/s)


                                                     Offset Voltage : 2.5V
 20    Acceleration Sensor Signal   IG.ON                                                 V
                                                     Range : 0.35V~4.65V (-1.8g~1.8g)


 15    Yaw Rate Sensor Ground       ALWAYS           GND LEVEL




 35    CAN High                     IG.ON




 14    CAN Low                      IG.ON



                                    BRAKE ON         High : 0.8*IGN Voltage or more       High : V
 30    Brake Light Switch
                                    BRAKE OFF        Low : 0.3*IGN Voltage or less        Low : V




                                                41               Chonan Technical Service Training Center
ESP (Electronic Stability Program)

 3) Wiring Diagram

 - ABS8




                                     42   Chonan Technical Service Training Center
ESP (Electronic Stability Program)



 - ESP8




                                     43   Chonan Technical Service Training Center
ESP (Electronic Stability Program)




                                     44   Chonan Technical Service Training Center

				
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