No Forward Or Reverse No Input Or Output Speed Signal After Valve Body Installation Or Replacement - keywords drive inoperative ISS OSS slip VSS

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Technician may comment that the vehicle has no forward or reverse or no input or output speed signal after valve body installation or replacement.

This may be caused by the installation of the incorrect center support fluid passage seal (20) or upper valve body assembly (304). The center support fluid passage seal (20) for the 6L50 is approximately 5/16" (8 mm) taller than the seal used on the 6L80 / 6L90. The 6L50 seal can also be identified by the metal tabs or "wings" extending from the ends of the seal. The shorter 6L80 / 6L90 part will not seal the valve body to the center support resulting in an internal fluid leak. Also, the 6L50 upper valve body center support oil transfer holes are in a different location vs. the 6L80 / 6L90 valve body. Installation of the 6L80 / 6L90 upper valve body may result in an internal fluid leak with no forward or reverse. Finally, installation of a 6L80 / 6L90 upper valve body will not place the input and output speed sensors close enough to their respective drums to generate a speed signal.

If these conditions are encountered the P/Ns used in the repair should be checked to verify that they are the appropriate parts for the 6L50 (MYB).

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.