Diagnostics, Fault-Tracing

Diagnostics, fault-tracing





General
All modules in the network have integrated diagnostic functions. Each module, ABS for example, checks:
- its internal functions.
- the function of cables and components directly connected to the module.
- that the expected message is received at the correct interval.
The function (open-circuit, short-circuit etc) of the communication cables is checked by the CDM.

Insulating relay
The CDM has a relay connects and disconnects the CAN network to the data link connector (DLC) in the center console. During normal driving the CAN network is not connected to the data link connector (DLC). The isolation relay closes and connects the data link connector to the network with a special communication line command to the CDM.

Diagnostics
If a module finds a fault the following occurs:
- the diagnostic trouble code (DTC) is stored locally in the module, for certain types of fault the module connects an emergency program.
- the module sends out a fault message on the net.
- fault message is received by the other modules which connect emergency programs as necessary (for example in case of loss of memory from a sensor).
- The CDM warns the driver by lighting a warning lamp(s) in the instrument panel.

Fault-tracing
VIDA is used to read out and if necessary erase any diagnostic trouble codes (DTC)s. VIDA then functions as it does for other cars, step by step instructions for the fault-tracing are given.