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.
The TBCM detects voltage greater than 5.2 volts in the manual apply switch 5-volt reference circuit.
The TBCM detects voltage less than 4.8 volts in the manual apply switch 5-volt reference circuit.