No Reverse Hot, Transaxle Slips in Reverse When Hot, Bump in Reverse Hot (Retighten Valve Body Bolt (379) and Replace Channel Plate Gasket)

Some customers may comment that the vehicle slips in reverse when hot, no reverse when hot, or they feel a bump when shifted into reverse when hot.

There are multiple possible causes. Listed below are some of the possible causes:

Follow the procedure below for diagnostic tips and repair procedures.

1. Inspect the reverse cover retaining ring for proper seating/retention.

•	If the ring is incorrectly seated, reset the retaining ring.

•	If the retaining ring is properly seated, continue with the next step.

2. Perform a transaxle line pressure check in reverse. This will test the reverse servo piston seal for leaks. Refer to Line Pressure Check Procedure, SI Document ID #634307.

•	If the line pressure test is out of specification, inspect/repair the reverse servo piston seal. Refer to:

-	Reverse Servo Replacement w/3.4L Engine SI Document ID #1485540

-	Reverse Servo Replacement w/3.8L Engine SI Document ID #1485543

•	If the line pressure test is within specification, continue with the next step.

3. Remove the transaxle side cover. Refer to the appropriate SI Document.



4. Inspect valve body bolt (379) for breakaway torque of 16N·m(11 lb ft).

•	If valve body bolt (379) is found loose, replace the channel plate gaskets, P/N 24206391, and retighten the valve body. Refer to Control Valve Body Replacement SI Document ID #839835.

•	If the valve body bolt is found not to be loose, continue with the next step.

5. For additional reverse diagnostic information, refer to Slips in Reverse or No Reverse SI Document ID #54866.

Parts are currently available from GMSPO.

For vehicles repaired under warranty, use: