On-Board diagnostics is an automotive term which is a term that refers to a self diagnostic and reporting ability of a vehicle. It gives information of health conditions of any kind of vehicles to a man who is an owner of car or a mechanic. The OBD diagnostic information's are available from early of 1980s on the on-board computers. The early OBD just illuminate a malfunction indicator light only. But if problems occur, it could not give any important information about the problem as well as the solving procedure of these problems. On the other hand modern OBD can transmit diagnostic trouble codes with very fast digital communication port which can identify false easily and remedy malfunctions in the vehicle. There are several types of OBD diagnostic are there. Such as OBD 1, OBD 1.5, OBD 2, EOBD, EOBD 2, HDOBD,chilton auto repair manual etc. Volkswagen introduces the first OBD system. It upgrades day by day and now heavy duty OBD has introduced to detect the problems in the vehicles. In 1987s OBD II has diagnostic has introduces which is more advanced than OBD I in both capability as well as standardization with the help of Audi Repair manuals. The type of OBD II diagnostic connector and its pinout, messaging format and electrical signal protocol is the main specifications of OBD II diagnostic system. As a result of these specifications it provides an extensible list of DTC. The location of OBD II is somewhat different from OBD I. OBD II diagnostic lies within two feet from the staring wheel where as OBD I sometimes lie under the hood of the car. OBD II diagnostic connector has 16 pins and SAE J1962 defines that pins as: First pin is manufacturer discretion, second is bus positive line of SAE J1850 PWM as well as SAE -1850 VPM. Third is for ford DCL positive, forth is chassis ground, fifth is for signal ground. Tenth is for bus negative line of SAE J1850 PWM only, eleventh is ford DCL negative, sixteenth is for battery voltage and so on. When a troubleshooting problem occur inside a vehicle the OBD II creates necessary data from the engine control unit to the output monitor. OBD II diagnostic is more advanced system that provides an important role in mechanic field as well as for a person who has a car. It also provides information to remove all faults and make the vehicle free and smooth like before.
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