This bulletin applies to 2007-2013 Chevrolet Silverado vehicles equipped with the Allison LCT1000 5-speed or 6-speed transmission, where the vehicle may not move in forward or reverse.
Transmission line pressure is found to be correct with a turbine speed reading of more than 200 rpm below engine speed in park or neutral. In some cases, the turbine speed may be at or near “0” on the Tech II scan tool.
Inspect for metal debris in the torque converter clutch valve. The torque converter clutch valve will be stuck in the stroked position.
The debris must be removed and all valves and bores in the pump body must be cleaned to ensure that each of the valves moves freely in their pump cover bores.