Signal Too Low

Signal too low

IMM-312 Communication with engine control module (ECM)

Checking for a short-circuit
Check the wiring for permanent short-circuit to ground according to Checking wiring and terminals. Permanent fault Checking Wiring And Terminals. Permanent Fault or an intermittent short-circuit to ground according to Checking wiring and terminals. Intermittent faults Checking Wiring And Terminals. Intermittent Faults.

Caution! The engine control module (ECM) must not be disconnected until at least 10 seconds after the ignition has been switched off and the engine cooling fan (FC) has stopped.

- On cars with the EMS 2000 engine management system, the cable between immobilizer control module #4 and engine control module (ECM) #B56.
- On cars with the Melco 1 engine management system, the cable between immobilizer control module #4 and engine control module (ECM) #C7 (C=12 pin).

Other information
- For information about signals and other values, see Signal specification Signal Specification, Immobilizer.









Select Continue when the fault has been remedied.

Continue - Verification

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Verification




Verification

Verification

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








- Ignition off.
- Reinstall the connectors, components etc.
- Start the engine.
Do not start the engine if there is a communication fault between the engine control module (ECM) and the immobilizer.

Does the engine start?

Yes - VERIFIED

No - VERIFICATION FAILED

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VERIFIED - FAULT FOUND

VERIFICATION FAILED - Fault-tracing information

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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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FAULT-TRACING FAILED - FAULT-TRACING FAILED

Attempt New Test - Checking for a short-circuit

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