Communication Problems with the Engine Control Module (ECM)

Communication problems with the engine control module (ECM)

Checking diagnostic trouble codes (DTCs) in the central electronic module




Checking diagnostic trouble codes (DTCs) in the central electronic module

Checking other diagnostic trouble codes (DTCs)
In the event of communication problems, the fault may exist in other parts of the communications network.
The role of the central electronic module is to generally control the communications network and to store diagnostic trouble codes (DTCs) in the event of communication problems between control modules.
If there are diagnostic trouble codes (DTCs) stored for communication problems in the central electronic module, stop the fault tracing and fault trace the central electronic module.

Were diagnostic trouble codes (DTCs) for communication problems stored in the central electronic module?

Yes - Stop the fault tracing and fault trace the central electronic module.

No - Checking diagnostic trouble codes (DTCs) in the engine control module (ECM)

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Checking diagnostic trouble codes (DTCs) in the engine control module (ECM)
The diagnostic trouble code (DTC) is stored because the torque signal or engine speed signal from the engine has been missing for more than 500 ms. The signals are used by the brake control module for control the stability function.
If there are any diagnostic trouble codes (DTCs) stored for the engine control module (ECM), these must be fault traced first.

Were diagnostic trouble codes (DTCs) for the engine control module (ECM) stored?

Yes - If there are any diagnostic trouble codes (DTCs) stored for the engine control module (ECM), these must be fault traced first.

No - Checking diagnostic trouble codes (DTCs)

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Checking diagnostic trouble codes (DTCs)




- Ignition on
- Wait approximately 60 seconds
- Read off the status of the diagnostic trouble code (DTC).





Is the status of the diagnostic trouble code (DTC) permanent?

Yes - Checking wiring and terminals

No - Intermittent fault

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Checking wiring and terminals




- Ignition off.
Check the brake control module connector. Check for damaged or bent terminal pins. Check for contact resistance and oxidation.
Check the wiring for CAN communication between terminals #A11 (#A11) and #B13 (#B13) and between terminal #15 (#A15) and #B1 (#B11). Check for an open-circuit. Check for a short-circuit to ground. Check for a short-circuit to supply voltage.
Check that the wiring is not too close to a source of interference such as a car-phone etc.
Remedy as necessary.

Other information
- To check the wiring and connections, see Checking wiring and terminals Checking Wiring And Terminals.

Continue - Verification

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Fault-tracing information




Information

Fault-tracing information
The fault should have been detected and remedied. As this is not the case fault-tracing has failed.
Exit fault-tracing for this diagnostic trouble code (DTC) or make another attempt.

Do you want to exit fault-tracing?

Yes - Exit Fault-Tracing

No - Attempt New Test

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Attempt New Test - Checking diagnostic trouble codes (DTCs) in the central electronic module

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Verification




Hint: After carrying out the repair, check that the fault has been remedied.








- Ignition off
- Reconnect the connectors, reinstall components etc.
- Test drive the car. See Test Drive Form (DSTC (dynamic stability and traction control) /brake control module), description Test Drive Form (DSTC (Dynamic Stability And Traction Control) /Brake Control Module), Description
- Ignition on.
Read off the status of the diagnostic trouble code (DTC).





Is the status of the diagnostic trouble code (DTC) intermittent?

Yes - Verification completed

No - Fault-tracing information

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Intermittent fault

Hint: The status of the diagnostic trouble code (DTC) indicates that the brake control module has previously registered a fault but that the fault is not active.

Check the connectors for the brake control module and the engine control module (ECM). Check for contact resistance and oxidation.
Also check that the wiring for CAN communication is not too close to a source of interference such as a car-phone etc.
Remedy as necessary.

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