Diagnostic trouble code (DTC) information CEM-1C08

Condition 

Fig 1: Freewheel Generator

Courtesy of VOLVO CARS OF NORTH AMERICA.

The central electronic module (CEM) communicates with the alternator control module (ACM).

The diagnostic trouble code (DTC) is stored if the central electronic module (CEM) receives information from the alternator control module (ACM) indicating an internal mechanical fault in the generator (GEN).

The diagnostic trouble code (DTC) can be diagnosed at engine speeds (RPM) above 600 RPM.

Substitute Value 

• None.

Possible Source 

• Defective auxiliaries belt and belt tensioner
• Damaged freewheel
• Damaged generator (GEN).

Fault symptom[s] 

• The "Generator not charging" warning lamp is lit when the engine is running
• The battery discharges
• Low rotation speed in the starter motor
• Noise from the generator (GEN)
• Noise from the belt transmission
• The engine judders under acceleration.