Circuit/System Description
WARNING: This page is about a different car, the 2009 Cadillac DTS. However, it is still accessible from the selected car via links, so may be relevant.
The transmission control module (TCM) continuously monitors the system voltage on the ignition voltage and the battery voltage circuits. Lower than normal or higher than normal voltage may not operate the transmission control solenoids properly. Improper solenoid operation may cause erratic transmission operation and may result in internal transmission damage.