Conditions for Running the DTC

WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2012 GMC Yukon XL, 2012 GMC Yukon, 2012 Chevrolet Tahoe, 2012 Chevrolet Suburban, and 2012 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.

Ignition voltage is between 8.6 volts or greater.
The TCM temperature is between 0°C (32°F) and 170°C (338°F) for 0.25 seconds.
DTC P0634 and has not set this ignition.