TCM killed by jump-start
This bulletin applies to a host of GM vehicles, including 2005-2010 Chevy Cobalt; 2006-2010 Chevy HHR, Chevy Express, GMC Savana; 2005-2006 Pontiac Pursuit; 2007-2010 Pontiac G5 and 2005-2097 Saturn Ion, equipped with the 4T40-E, 4T45-E or 4L60-E automatic transmission.
As a result of jump starting, the TCM (transmission control module) is possibly shorted to battery voltage. It has been found that if the positive battery jump start post/terminal cover is removed and/or missing, and the TCM comes in contact with the positive battery jump start post/terminal during diagnosis and/or service, the TCM will be damaged and require replacement.
Prior to removing the TCM from its mounting bracket, disconnect the negative battery cable. If service requires the negative battery cable to be installed for diagnostic purposes, unplug the TCM before it is removed from its mounting bracket. Unplugging the TCM will eliminate the possibility of damaging the module.
Caution: Control module damage may result when the metal case contacts battery voltage. DO NOT contact the control module metal case with battery voltage when servicing a control module, using battery booster cables, or when charging the vehicle’s battery. DO NOT use the TCM or its mounting bracket/fasteners as the ground connection when jump starting.
The location of the positive battery jump post/terminal for each vehicle (excluding Express and Savana) is shown in the following illustrations.