General Information for AutoDoctor007 AUT610 Auto Scanner
Diagnostic Trouble Codes (DTC) are codes that are stored by the on-board computer diagnostic system in response to a problem found in the vehicle. These cods identify a particular problem area and are intended to provide you with a guide as to where a fault might be occurring within a vehicle. This section explains the basic elements of fault codes for J1587/J1708 and J1939 date bus protocols, how to view these codes on Auto Scanner AUT610, and what they mean. Each fault code on Heavy Duty Auto Scanner AUT610 contains three distinct pieces of information, as described below.
J1587/J1708 fault codes consist of the following, in this order:
- Subsystem Identifier (SID) – Indicates what function on the ECU has failed.
- Failure Mode Indicator (FMI) – Indicates in what way the function failed.
- Occurrence (OC) – Indicates the Occurrence times of fault codes.
J1939 fault codes consist of the following, in this order:
- Suspect Parameter Number (SPV) – Indicates what function on the ECU has failed.
- Failure Mode Indication (FMI) – Indicates in what way the function failed.
- Occurrence (OR) – Indicates the Occurrence times of fault codes.
SAE J1708, SAE J1587 and SAE J1939 are automotive diagnostic protocol standard developed by the Society of Automotive Engineers (SAE).
SAE J1708 is a standard used for serial communications between ECUs on a heavy duty vehicle and also between a computer and the vehicle. With respect to Open System Interconnection model (OSI), J1708 defines the physical layer. Common higher layer protocols that operate on top of J1708 are SAE J1587 and SAE J1922.
SAE J1587 is an automotive diagnostic protocol standard developed by the Society of Automotive Engineers (SAE) for heavy-duty and medium-duty vehicles built after 1985, The J1587 protocol uses different diagnostic connectors. Up to 1995, individual OEMs used their own connectors. From 1996 to 2001, the 6-pin Deutsch. Some OEMs still use the 6-pin Deutsch. It has mostly been used for US made vehicles.
SAE J1708 makes up the physical and date link layers while SAE J1587 makes up the transport and application layers with respect to the OSI model. SAE J1587 is used in conjunction with SAE J1708 for automobile communication.
SAE J1939 is the vehicle bus standard used for communication and diagnostics among vehicle components, originally by the car and heavy duty truck industry in the United States.
SAE J1939 is used in the commercial vehicle area for communication throughout the vehicle. With a different physical layer it is used between the tractor and trailer. This is specified is ISO 11992.
SAE J1939 can be considered the replacement for the older SAE J1708 and SAE J1587 specifications.
SAE J1939 has been adopted widely by diesel engine manufacturers. One driving force behind this is the increasing adoption of the engine Electronic Control Unit(ECU), which provides one method of controlling exhaust gas emissions within US and European standards. Consequently, SAE J1939 can now be found in a range of diesel-powered applications: vehicles (on-and off-road), marine propulsion, power generation and industrial pumping.
Applications of J1939 now include off-highway, truck, bus, and even some passenger car applications.