Diagnostic Trouble Code (DTC) Information CEM-1B01

Condition

NOTE:

Only on vehicles with the function automatic start/stop of engine.

The central electronic module (CEM) monitors the main battery diode and its associated functionality. The battery diode is used as a safety function if the secondary battery cannot supply enough energy to the vehicle's consumers while the starter motor runs when the engine is restarted after an auto stop.

The diagnostic trouble code is stored if the control module detects:

The voltage difference between the main battery and the secondary battery exceeds 1 V at restart after auto stop (hot crank).
Incorrect value runs longer than 0.2 seconds.

The control module's test for the diagnostic trouble code (DTC) starts in the event of:

At restart after auto stop (hot crank).

NOTE:

The control module can only detect the fault once the test has been started and the diagnostic trouble code (DTC) is stored when the conditions are met.

Substitute Value

None.

Possible Source

Open-circuit on the cable between the main battery and main battery diode.
Damaged battery diode.

Fault symptom[s]

Driving/Automatic start/stop of engine/Does not work
Idling/Automatic start/stop of engine/Does not work