Quick Test Information

The central electronic module (CEM) has built-in functions for regulating the alternator (alternator control module (ACM)).

To charge the battery optimally, output voltage from the alternator is calculated based on the calculated battery temperature. The central electronic module (CEM) calculates battery temperature from outside temperature, which is obtained from the outside temperature sensor.

Depending on the vehicle's ambient temperature and/or if the vehicle has been without power, the calculated battery temperature (read temperature) may differ slightly from the battery's actual temperature for up to 24 hours afterwards.

In the following tests, battery temperature in the central electronic module (CEM) is changed, thereby changing voltage from the alternator.

The test is divided into two parts - an automatic test and a manual test.

Select one of the alternatives below: 

1. Automatic test of alternator function.

   Refer to AUTOMATIC TEST OF ALTERNATOR FUNCTION 

2. Manual test of alternator function.

   Refer to MANUAL TEST OF ALTERNATOR FUNCTION 

Fig 1: Freewheel Generator

Courtesy of VOLVO CARS CORPORATION