I believe most of you who have got in touch with vechiel diagnostic tools must be familiar with the concepts of OBDII ,JOBD and DTC.But still have many newers don't much about the three concepts.
OBDII is the abbreviation of On-Board Diagnostic Version II.It is a system that developed by the Society of Automative Engineers and designed to standardize automotive electronic diagnosis.Since 1996,the majority of the vehicles that sold in the United States are completely OBDII compliant.
The OBDII system monitors the operation condition of the engine and the working condition of the exhaust gas' processing system,once there may cause the excessive emission,the system will give the warning.When the system has something wrong,the MIL lamp or the Check Engine warning lamp will be lighted, meanwhile, the OBD system will save the error in memory,then vehicle maintenance technicians will locate the error part quickly and accurately by reading the error information that stored in memory with the standard diagnostic tool and diagnostic interfaces.
Now vehicle maintenance technicians can use the same tool to test all the OBDII compliant vehicle without using special adapters.The SAE established guidelines of the universal connector which called the DLC, the standard location for the DLC and the standard list of diagnostic trouble codes that used by all manufactures.
The JOBD is the system special for Japanese manufactured vehicles.It is designed to monitor emission control systems and key engine components.And the functions of JOBD are the same with the OBD system.
The DTC is the abbreviation of Diagnostic Trouble Codes.They are stored by the OBD systems in response to an error that found in the vehicle and they can identify a particular error area and offer you the guidance of where anerror might be occurring within a vehicle.
The DTC consists of a five-digit alphanumeric code.The first one is an letter,the "B" indicates "Body"; "C" is "Chassis"; "P" is "Powertrain"; "U" is "Network";The last four are all numbers which are providing additional information of the operating conditions.The second one is represent the code type and manufacturer specific;the third one indicates the sub-system and the fourth and the fifth are all used to identify specific malfunctioning section of the system.
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