Circuit/System Description

WARNING: This page is about a different car, the 2010 Pontiac G5 and 2010 Chevrolet Cobalt. However, it is still accessible from the selected car via links, so may be relevant.

The body control module (BCM) has designated B+ circuits for monitoring vehicle system voltage, fed by the BCM 2 fuse and the SDM or XM/ONSTAR fuse. Fuse 24 in the BCM will either be labeled SDM or XM/ONSTAR, depending on vehicle content. The BCM monitors the system voltage to ensure that the voltage stays within the proper range. Damage to components and incorrect data may occur when the voltage is out of range. The BCM monitors the system voltage over an extended length of time. If the BCM detects the system voltage is outside an expected range for the calibrated length of time, or the BCM battery sense circuits differ by 3 volts, DTC B1517 5A will set. Other modules also monitor system voltage. The system voltage message is sent to the other modules and will default to 12.9 volts if DTC B1517 5A sets.