Communication Problems With the Central Electronic Module
Communication problems with the central electronic module
Checking other diagnostic trouble codes (DTCs)
Hint: 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 (DTC) stored in the central electronic module these must be fault traced accordingly.
- Ignition on
- Wait approximately 60 seconds
- Read off diagnostic trouble codes (DTCs).
If there are diagnostic trouble codes (DTCs) for communication problems stored for the brake control module in the central electronic module, these must be fault traced first.
Were diagnostic trouble codes (DTCs) stored in the central electronic module?
Yes - DONE
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
- 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 brake control module terminal #11 (#A11) and central electronic module terminal #17B and between brake control module terminal #15 (#A15) and central electronic module (CEM) terminal #18B. 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 carphone 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 - FAULT-TRACING FAILED
No - Attempt New Test
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Attempt New Test - Checking other diagnostic trouble codes (DTCs)
FAULT-TRACING FAILED - FAULT-TRACING FAILED
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Verification
Verification
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 - VERIFIED
No - VERIFICATION FAILED
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VERIFICATION FAILED - Fault-tracing information
VERIFIED - Fault Found
PAPER - No Fault Found
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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 central electronic module. 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 carphone etc.
Remedy as necessary.
Continue - DONE
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Fault-tracing information
Information
Fault-tracing information
If the fault is intermittent, do not verify fault-tracing if the fault does not recur.
It is possible to view the information again, or leave fault-tracing for this diagnostic trouble code (DTC).
Do you want to view the information again?
Yes - Attempt New Test
No - Fault Found
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Attempt New Test - Checking other diagnostic trouble codes (DTCs)
FAULT-TRACING FAILED - Fault Found
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