Diagnostic Trouble Code (DTC) Information

Diagnostic trouble code (DTC) information ECM-720A

Condition
The engine control module (ECM) contains a code for the immobilizer which is unique to each car. Before the engine can be started, the immobilizer code is checked to ensure that it corresponds to both the central electronic module (CEM) and the engine control module (ECM). The diagnostic trouble code (DTC) (Faulty signal) will be stored if the code for the immobilizer does not match.
The diagnostic trouble code (DTC) (Signal missing) will be stored if there is no communication between the central electronic module (CEM) and the engine control module (ECM) so that the immobilizer code cannot be checked.
The diagnostic trouble code (DTC) (Signal too high or signal too low) will be stored if the engine control module (ECM) is not programmed or if an internal fault is detected in the engine control module (ECM).
The diagnostic trouble code (DTC) can be diagnosed when the ignition is switched on.

Substitute value
None.

Possible source

Signal too high
- The engine control module (ECM) is not programmed and has no code for the immobilizer
- Damaged engine control module (ECM).

Signal too low
- Damaged engine control module (ECM).

Faulty signal
- The engine control module (ECM) has an incorrect code for the immobilizer
- The central electronic module (CEM) has an incorrect code for the immobilizer
- Damaged engine control module (ECM).

Signal missing
- Open-circuit in the communication between the central electronic module (CEM) and the engine control module (ECM)
- The central electronic module (CEM) is not programmed and has no code for the immobilizer
- Damaged central electronic module (CEM).

Fault symptom[s]
- The starter motor turns but the engine does not start.