Conditions for Setting the DTC

WARNING: This page is about a different car, the 2008 GMC Yukon and 2008 Chevrolet Tahoe. However, it is still accessible from the selected car via links, so may be relevant.

The TCM has detected an internal overtemperature condition greater than 141°C (286°F) for 2 seconds.
The ignition voltage is greater than 18 volts and the TCM temperature is greater than 50°C (122°F).