Diagnostic Trouble Code (DTC) Information CEM-1C04

Condition 

Fig 1: Identifying Central Electronic Module (CEM)

Courtesy of VOLVO CARS CORPORATION

The central electronic module (CEM) checks the 30-supply.

The diagnostic trouble code (DTC) is stored if the control module registers that the 30-supply exceeds 17 volts for at least 5 minutes.

The diagnostic trouble code (DTC) can be diagnosed when the ignition is switched on.

Substitute Value 

• None.

Possible Source 

• Damaged generator (GEN)
• Damaged charge regulator
• Damaged battery.

Fault symptom[s] 

• The "Generator not charging" warning lamp is lit when the engine is running
• Alternator and charge regulator/Power supply problems
• The headlamp bulb blows
• The "Generator not charging" warning lamp does not light when the ignition is switched on
• Low rotation speed in the starter motor
• Starting/Engine does not start/Unsure when/at all times
• The electrolyte in battery boils with the engine running
• The battery discharges.