Conditions for Setting the DTC

WARNING: This page is about a different car, the 2007 GMC Sierra and 2007 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.

DTC C1112 will set as current DTC, if one of the following conditions is true:

The TBCM detects an open in the relay control active low circuit.
The TBCM detects short to ground in the relay control active low circuit.
The TBCM detects short to battery positive in the relay control active low circuit.
The TBCM detects a open power circuit from fuse 65 or 61.