Diagnostic Trouble Code (DTC) Information

Diagnostic trouble code (DTC) information ECM-721A

Condition
The engine control module (ECM) contains a code for the immobilizer which is unique to each car. The unique code is checked so that it corresponds to the central electronic module (CEM) and the engine control module (ECM). The electronic immobilizer has another criterion that must be met before it allows the engine to start. A check is performed via CAN communication to ensure that the hardware series number on the brake control module (BCM) corresponds to the number stored in the engine control module (ECM). The hardware series number is automatically stored when downloading software to the engine control module (ECM). If the hardware series number corresponds to the engine control module (ECM) and the brake control module (BCM), the electronic immobilizer will allow the engine to start.
The diagnostic trouble code (DTC) (Signal too high) is stored if an internal fault is registered in the engine control module (ECM)
The diagnostic trouble code (DTC) (Faulty signal) is stored if the hardware series number in the brake control module (BCM) does not correspond to the number stored in the engine control module (ECM).
The diagnostic trouble code (DTC) (Signal missing) is stored if the engine control module (ECM) registers that there is a fault in the CAN communication between the engine control module (ECM) and the brake control module (BCM).
The diagnostic trouble code (DTC) can be diagnosed when the ignition is switched on.

Substitute value
None.

Possible source

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

Faulty signal
- The programmed hardware series number in the engine control module (ECM) does not correspond to the relevant hardware series number in the brake control module (BCM).

Signal missing
- Fault trace the brake control module (BCM)
- Open-circuit or short-circuit in the CAN wiring between the engine control module (ECM) and the brake control module (BCM).

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