Conditions for Setting the DTC
WARNING: This page is about a different car, the 2017 Cadillac ATS. However, it is still accessible from the selected car via links, so may be relevant.
DTC B3881 02
The BCM detects a short to ground in the left rear tail lamp control circuit.
DTC B3882 02
The BCM detects a short to ground in the right rear tail lamp control circuit.