A/T - Delayed Forward Engagement, Slipping on Take Off

Bulletin No. T 86-14
File in Group 7
Number 127
Corp. Ref. No. 806 7601
Date Nov. '85
SUBJECT: DELAYED FORWARD ENGAGEMENT AND SLIPS ON TAKE OFF OR 2-3 UPSHIFT BUMP

MODELS AFFECTED: 1985 - 1986 DE VILLE/FLEETWOOD

Some 1985 and 1986 Cadillac equipped with a THM440-T4 transaxle may experience conditions of delayed forward engagement and slipping on take off from stops or a 2-3 upshift bump. These conditions can be caused by a leak at the seals in the hydraulic circuits controlling apply and release of the 1-2 band.

FIGURE 1 - SERVO PIPE TO CASE SEALS:

FIGURE 2 - SERVO PIPE TO CONTROL VALVE BODY SEAL LOCATIONS:

Seals are included at both ends of the apply and release pipes (refer to Figures 1 and 2) and on the servo piston. Damaged seals in any position will effect operation of the servo. Leaking apply circuit seals will cause delayed engagement (forward only) and slipping when in first or second gears. Seal leaks in the release circuit will cause a 2-3 upshift bump or tie up, due to inadequate band release (severe release circuit leak could result in a 2-3 upshift slip).

When performing transaxle service closely inspect the transaxle oil condition. Presence of burnt oil or metal debris indicates internal transaxle wear; Service via replacement with a SRTA transaxle or overhaul per procedures listed in the appropriate Service Information Manual. If the transaxle oil is not burnt and debris is not present inspect the servo pipe seals at both ends of each pipe and the 1-2 servo piston seals for damage. Replace any damaged seal as outlined in the appropriate Service Information Manual. When installing the servo pipes into the control valve body, ensure seal damage does not occur. Road test to ensure proper transaxle operation.
For Warranty purposes use labor operation T6133 for 2.8 hours when replacing servo pipe to control valve body seals. Use Labor Operation T6134 for 1.0 hour to replace servo pipe to case seals. Use Labor Operation K6626 for 0.3 hour to replace servo piston seals.