Diagnostic Trouble Code (DTC) Information ECM-A10D

Condition 

The engine control module (ECM) communicates with the alternator control module (ACM) via a standardized serial communication method, Local Interconnect Network (LIN).

The diagnostic trouble code (DTC) (Signal too high/Signal too low) is stored if the alternator control module (ACM) transmits information about an electrical fault to the engine control module (ECM).

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

The diagnostic trouble code (DTC) (Faulty signal) is stored if alternator control module (ACM) transmits information to the engine control module (ECM) about an mechanical fault in the generator (GEN) (the engine is running above a certain speed but the generator (GEN) is stationary.

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

The diagnostic trouble code (DTC) (Temperature too high) is stored if the alternator control module (ACM) transmits information to the engine control module (ECM) that the generator (GEN) temperature exceeds a certain value.

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

The diagnostic trouble code (DTC) (Faulty communication) is stored if the engine control module (ECM) registers interference in communication with the alternator control module (ACM).

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

Substitute Value 

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

Possible Source 

Signal too high / Signal too low 

• Battery charger with too high charge voltage has been connected previously
• Worn brushes (carbon)
• Damaged alternator control module (ACM)
• Damaged generator (GEN).

Faulty signal 

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

Temperature too high 

• The air ducts for the generator (GEN) are blocked.

Faulty communication 

• Contact resistance and oxidation in the terminals
• Short-circuit between the LIN wiring
• Open-circuit in the LIN wiring
• Internal fault in another control module in the same part of the LIN network
• Damaged alternator control module (ACM)
• Generator with a charge regulator not intended for LIN communication installed.

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
• The electrolyte in battery boils with the engine running
• The headlamp bulb blows.