Checking The Wiring

The diagnostic trouble code (DTC) is stored if there is no communication between the engine control module (ECM) and the alternator control module (ACM). This may be due to a fault in the signal cable between the control modules or a damaged communication device in one or both of the control modules.

HINT: This diagnostic trouble code (DTC) can be stored if a generator (GEN) with an alternator control module (ACM) (charge regulator) not intended for LIN communication is installed. 

Check the connector on the alternator control module (ACM). Check for contact resistance and oxidation.

Check the signal cable. Check for an open-circuit. Check for a short-circuit to ground. Check for a short-circuit to supply voltage.

Take readings between:

• Engine control module (ECM) #A46 (#A46) and alternator control module (ACM) #B2.

HINT: Another test to check the alternator's function is to perform Quicktest of alternator function. Found in VIDA vehicle communication under Central electronic module (CEM). VIDA is Volvo-specific scan tool. 

Remedy as necessary.

Other information 

• see CONNECTING THE BREAKOUT BOX
• see SIGNAL SPECIFICATION
• see CHECKING WIRING AND TERMINALS

Was a fault detected? 

• YES 

  Refer to INFORMATION 

• NO 

  Refer to REPLACING THE CONTROL MODULE