Defect Involved

General Motors has determined that a defect which relates to motor vehicle safety exists in certain 1993 Chevrolet 4-wheel drive S Model trucks equipped with 4L60-E automatic transmissions. These vehicles may develop significant wear on the low and reverse clutch, which may prevent the park pawl from engaging. This could allow a "no park" condition to occur while the engine is running. Unintentional movement of the vehicle could result in injury to persons in the path of the vehicle. If the ignition is turned off, however, the "no park" condition will not occur.

To prevent the possibility of this condition occurring, dealers are to:

1. Check the transmission fluid for contamination which will indicate if the low and reverse has had excessive wear. If the transmission shows excessive wear, the transmission will be replaced.

2. Remove the right side brace from transmission to transfer case.

3. Modify the transmission case hydraulic oil circuit to prevent the possibility of this condition the low and reverse piston from being applied in the park (P) range with the engine running if the transmission was produced prior to January 4, 1994.