The Service Information for 2008-2020 GM models equipped with the 6T40, 6T70, 6L50, 6L80, or 6L90 6-speed transmission; 9T45, 9T50, 9T60, or 9T65 9-speed transmission; or VT40 continuously variable transmission (CVT) has been updated to include a new danger statement for certain DTCs. The DTCs include P2724 (Solenoid Valve 5 Stuck On) on applicable 6-speed transmissions, P0747 (Solenoid Valve 1 Stuck On) on applicable 9-speed transmissions, and P2715 (Solenoid Valve 4 Stuck On) on applicable CVTs.
When servicing these transmissions with these particular DTCs set, be aware that the vehicle could move forward if it is started in Neutral. In some failure modes, the friction and steel plates for the first gear clutch may be burned so badly that they have been welded together (Fig. 3), which may result in possible vehicle movement.
Fig 3
The new danger statement for 6-speed transmissions reads, “If DTC P2724 is present, the vehicle will have forward propulsion while in neutral. Failure to keep the brake pedal depressed while shifting through the gear ranges may cause the vehicle to move forward, resulting in potential vehicle damage and possibly injury or death.” (Fig. 4) The statement for the other DTCs is similar.
Fig. 4
Regardless of the service procedure, it’s recommended to keep the brake pedal applied any time the vehicle is started.
– Thanks to Ron Caponey
