Conditions for Setting the DTC
WARNING: This page is about a different car, the 2007 Cadillac DTS. However, it is still accessible from the selected car via links, so may be relevant.
B2645 03
The DTC will set when the BCM detects the ambient light sensor signal voltage is below 0.196 volts.
B2645 07
The DTC will set when the BCM detects the ambient light sensor signal voltage is above 4.9 volts.