General Information
The diagnostic trouble code is stored when communication between Central electronic module (CEM) and relevant control module has been interrupted. There can be a number of causes for interruptions in the communication:
- Central electronic module (CEM) has stopped sending the signal that receiving control module (the control module that generated this fault code) expects.
- Intermittent open-circuit in one or both CAN cables in part of the network
- Intermittent short-circuits between the CAN cables
- Intermittent short-circuits between one of the CAN cables and ground or supply voltage
- Incorrect signal configuration in control module that set diagnostic trouble code. The fault can be due to a customer or workshop replacing a control module without downloading new software for the replacement.
If there is a diagnostic trouble code (DTC) for a communication fault in a control module, check whether diagnostic trouble codes (DTCs) have been stored in the central electronic module (CEM). Central electronic module (CEM) monitors the voltage level on the CAN-lines, and is the only control module that directly can set a diagnostic trouble code for short-circuiting to ground or to voltage for any of the leads. Central electronic module (CEM) shall not be replaced in case of CAN-fault, unless troubleshooting reveals that the module has an internal fault.
Corrective actions
- If there are diagnostic trouble codes stored in several control modules that indicate lost communication on the CAN-net, first try to troubleshoot diagnostic trouble codes in Central electronic module (CEM).
- If the problem is intermittent, erase the diagnostic trouble code and check that it is not generated again.
- If there are only diagnostic trouble codes that indicate lost communication on the CAN-net stored in the control module that generated this trouble code, try to solve the problem by downloading new software to the control unit.
- Check the cables in the controller area network (CAN) according to the following fault-tracing.
Other information
- see GENERAL INFORMATION ABOUT FAULT-TRACING IN THE CAN NETWORK
- Go to the tab software and program the control module with the latest software.
- Continue
Refer to VERIFICATION