Conditions for Setting the DTC

WARNING: This page is about a different car, the 2009 GMC Sierra, 2009 GMC Cab & Chassis Sierra, 2009 Chevrolet Silverado, and 2009 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The system monitors the voltage on the 2 high indicator control circuit.
If the TCCM detects a voltage of 1.6 V or less for 1.5 seconds when the 2 High indicator not commanded OFF.
The TCCM detects 3.4 V or more when the 2 High indicator is commanded ON.