Conditions for Setting the DTC

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2004 Oldsmobile Bravada, 2004 GMC Envoy XUV, 2004 GMC Envoy XL, 2004 GMC Envoy, and 2004 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.

When the BCM receives a courtesy lamp illumination request signal and the courtesy lamp supply voltage circuit is shorted to ground.
When the BCM is not receiving a courtesy lamp illumination request signal and the courtesy lamp supply voltage circuit is shorted to voltage or open only to the first splice from the BCM.
There is a loss of the rear fuse block TBC 3 battery supply voltage to the BCM for more than 1 second.