Transmission Management

TCM

Revised software is incorporated into the TCM to prevent the engine overheating during high speed running in fourth gear. While 4 is selected on the manual side of the gearshift selector, the TCM monitors time against a map of vehicle speed and transmission oil temperature. At vehicle speeds above approximately 192 km/h (120 mph), if calibrated time and temperature limits are exceeded, the TCM removes the inhibit that normally prevents an upshift to fifth, thus allowing an upshift to occur and the engine to run cooler. 5 minutes after the vehicle's speed decreases to below approximately 192 km/h (120 mph), the TCM reimposes the upshift inhibit and signals a downshift to fourth.