For 1990-2009 cars

# NO REVERSE WHEN TRANSMISSION IS HOT - POSSIBLE CAUSES

TO DIAGNOSE ANY THM 125 TRANSMISSION FOR A CUSTOMER COMMENT OF NO REVERSE WHILE TRANSMISSION IS HOT, FOLLOW THE SERVICE MANUAL "TROUBLE DIAGNOSIS" SECTION. IF LINE PRESSURE IS FOUND TO BE OK, CAREFULLY CHECK THE FOLLOWING LIST OF POSSIBLE CAUSES IN ADDITION TO THOSE LISTED IN THE SERVICE MANUAL. POSSIBLE CAUSES 1.MAKE CERTAIN THE CASE TO LO AND REVERSE CLUTCH HOUSING CUP PLUG ASSEMBLY IS FULLY SEATED AND NOT RESTRICTED. 2.CHECK FOR DAMAGED OR MISSING LO AND REVERSE PIPE WASHER AND "O" RING. 3.CHECK ALL DRIVEN SPROCKET SUPPORT BOLTS FOR 24 N.M (18 FT. LBS.) OF TORQUE. IF BOLT TORQUE IS FOUND TO BE LOW USE LOCTITE ON BOLT THREADS DURING REINSTALLATION. SEE FIGURE 1. 4.CHECK THE CASE COVER (VALVE BODY AND DRIVEN SPROCKET SUPPORT MATING SURFACES) FOR POSSIBLE DAMAGE, POROSITY, LEAK AND FLATNESS. ALSO CHECK THE DRIVEN SPROCKET SUPPORT SEALING SURFACE FOR THE SAME POSSIBLE CONDITIONS. 5.CHECK FOR CORRECT CASE TO CASE COVER GASKET AND CASE TO CASE COVER CENTRE GASKET. SEE PRODUCT SERVICE BULLETIN #113, GROUP 70, 1980, FOR FURTHER INFORMATION. 6.MAKE CERTAIN THE LO AND REVERSE CLUTCH INNER AND OUTER PISTON LIP SEALS ARE INSTALLED AS SHOWN IN FIGURE 2. THE LIP SEALS MUST BE INSTALLED WITH THE LIP FACING DOWN AND AWAY FROM THE CLUTCH APPLY RING. WITH THE LOW AND REVERSE CLUTCH PISTON INSTALLED INTO THE LOW AND REVERSE CLUTCH HOUSING, THE LIP OF THE LIP SEAL MUST CONTACT THE WALLS OF THE LO AND REVERSE CLUTCH HOUSING TO FORM A PROPER SEAL. INSTALLATION OF THESE SEALS IN ANY OTHER MANNER MAY CAUSE THE CONDITION MENTIONED.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.