Diagnostic Trouble Code (DTC) Information ECM-U012086

Condition 

Fig 1: Identifying Alternator Control Module (ACM)

Courtesy of VOLVO CARS CORPORATION

The engine control module (ECM) regulates the alternator charge voltage (via LIN communication) on request of the central electronic module (CEM) (via CAN communication). The diagnostic trouble code is generated if the engine control module (ECM) detects disrupted communication with the alternator control module (ACM).

The diagnostic trouble code can be diagnosed when the engine is running.

Substitute Value 

• The alternator control module (ACM) (charge regulator) charges with a fixed voltage of 13.8 V.

Possible Source 

• Internal fault in another control module in the same part of the LIN network.
• Damaged alternator control module (ACM) (charge regulator).

Fault symptom[s] 

• Battery discharged.