Signal Too Low
Signal too low
IMM-312 Communication with the engine control module (ECM)
Checking for a short-circuit
Check the wiring for a permanent short-circuit to ground according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault. Check the wiring for 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 is switched off and the engine cooling fan (FC) has stopped operating.
- On cars with the EMS 2000 engine management system, the cable between immobilizer control module terminal #4 and engine control module (ECM) terminal #B56
- On cars with the Melco 1 or Melco 2 engine management system, the cable between immobilizer control module terminal #4 and engine control module (ECM) terminal #C7 or #C28.
Other information
- For further information about signals and other values, see Signal specification Signal Description, Immobilizer.
Continue - Verification
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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 - Exit fault-tracing
No - Attempt New Test
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Attempt New Test - Checking for a short-circuit
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