Circuit/System Description
WARNING: This page is about a different car, the 2008 GMC Yukon and 2008 Chevrolet Tahoe. However, it is still accessible from the selected car via links, so may be relevant.
The body control module (BCM) has 2 circuits for monitoring vehicle 12V system voltage. The BCM B+ is supplied to terminal 3 X3 by the BCM fuse, and the high resolution B+ is supplied to the BCM terminal 10 X4 by the IPC fuse. The BCM monitors the system voltage on both circuits 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. If the BCM detects the system voltage on the high resolution B+ circuit is outside the normal range, DTC B1517 will set.