Since December 1, 2006, Beijing has banned not equipped with OBD vehicle ban sales in beijing.

In 2008 July, across the country have been implementing the vehicle equipped with OBD.

The OBD pin definition:

Standardization of OBD II

Design OBD program requirements the system to avoid confusion between the 16 pin diagnosis interface, which requires not only the use of standard, but also the use of a specific code and description of component manufacturers in the document, this is in order to achieve the unified and standard the following aspects of.

General terms and abbreviations

For example, the device provided the crankshaft position and speed information for computercalled the crankshaft position sensor, the abbreviation "CKP" are unified, computer are called "PCM".

General data diagnosis interface

16 pin diagnosis interface on each car was equipped with a standard shape and size, signal distribution for each pin of the same, and in the same position, mounted on the dashboard,somewhere between the left and the center line of the car dashboard right 300mm. It should be noted that, some terminal diagnosis interface, designated as a specific signal as shown inthe schedule. While the other terminal allows manufacturers to use, or not yet used in the current model car.

Universal diagnostic test mode

These test mode, is common to all OBD II cars, using the OBD II scan tool can test.

General scan tool

Meet the scan tool OBD II requirements necessary to access, and explain any vehicleemissions related diagnostic trouble codes, 16 pin connector cable beam scanning tools can be connected with the standard.

Universal diagnostic trouble codes

In the fault diagnosis for Shanghai, Guangzhou Buick accord sedan, self diagnosis system can display the standard OBD II fault code, such as "PO125", "PO204", representing the speed signal when the engine 5min has not reached 10 degrees and 4 injector output driver does not respond properly to the control signal. SAE J2010 provides a 5 bit standard fault code,first is a letter, 4 behind is the digital. The first letter indicates the system settings of fault codes. The current distribution of letters 4: "P" stands for power system, "B" represents the body, "C" represents the chassis, "system u" represent undefined. Second characters are 0,1, 2 or 3, meaning is as follows: 0 -- SAE (America society of Automotive Engineers) general fault code definition: 1 -- automobile manufacturers extends the definition of fault code; 2 or 3-- with system character (P, B, C or U) of different. Power system fault codes (P) of 2 or 3 by the SAE reserved for future use; body or chassis fault code 2 for manufacturers to retain,body or chassis fault code 3 is retained by the SAE. Third bit character representation of faultsystem: 1 -- fuel or air metering fault; 2 -- fuel or air metering fault; 3 -- ignition failure or engine misfire; 4 -- auxiliary emission control system fault; 5 -- a car or idle speed control system fault; 6 -- computer or output circuit fault. 7 -- 8 -- the transmission control system;control system. The last two characters show trigger fault code condition. Different sensors,actuators and circuit allocation of different number of sections, section small numbers represent a general fault, namely the general fault code; larger digital said spreading codes,provides more specific information, such as voltage is low or high, slow response, or signal out of range.

A standardized protocol

Require manufacturers to use multiplex communication in the same language, communicationbetween PCM and its sensors and actuators, and receiving and transmitting of diagnostic information and diagnostic tools between. OBD II standards engine management system for each of the monitored circuit, according to the operation condition of specially set such as warm machine cycle, driving cycle, OBD II journey, OBD II drive cycle and similar conditions, inmonitoring the sequence of detecting fault location, fault code, lit and extinguished the fault lamp, and eliminate the fault code. Here, the so-called monitor sequence is a running process,is used to test the function of a system or component operation regulations. For example, the computer can be opened or closed in the EGR valve deceleration, and monitor the MAPsensor, in order to observe whether the EGR valve in the work; or when cruising, computeropen or closed canister purge, to observe the oxygen sensor signal, so that it cansimultaneously test two part.