For 1990-2009 cars

# ERRATIC/NO UPSHIFTS/THM 700 R4 DIAG. WORN GOV. GEAR

IN DIAGNOSING ANY THM 700-R4 TRANSMISSIONS FOR ERRATIC OR NO UPSHIFTS, THE CAUSE MAY BE FROM A WORN GOVERNOR GEAR. THE CAUSE OF THE WORN GOVERNOR GEAR MAY BE FROM ONE OR MORE OF THE FOLLOWING CONDITIONS: 1. THE OUTPUT SHAFT TO INPUT CARRIER ASSEMBLY SNAP RING CAME OFF. 2. METAL SCALE ON THE OUTPUT SHAFT GEAR. 3. THE GOVERNOR DOWEL PIN DIMENSION MAY BE INCORRECT. 4. AN INCORRECT GOVERNOR GEAR MAY HAVE BEEN INSTALLED. WHEN SERVICING ANY THM 700-R4 TRANSMISSION FOR AN ERRATIC OR NO UPSHIFT CONDITION, REFER TO THE FOLLOWING DIAGNOSIS CHART: FOLLOW GUIDELINES GIVEN IN YOUR SERVICE MANUAL FOR SERVICING THE TRANSMISSION GOVERNOR GEAR. CONDITION: GOVERNOR GEAR IS WORN IN AN "APPLE CORE" SHAPE (SEE FIGURE 1). CAUSE: 1. FLASH, SCALE OR NICKS ON THE OUTPUT SHAFT GEAR. 2. INCORRECT GOVERNOR GEAR (THM 350-C TYPE). CORRECTION: 1. REPLACE GOVERNOR GEAR (P/N 8642928) WIRE BRUSH OUTPUT SHAFT GEAR TO REMOVE SCALE OF FLASH. REPLACE OUTPUT SHAFT IF NICKED. 2. REPLACE GOVERNOR GEAR (P/N 8642928) --DO NOT-- USE THM 350-C TYPE AS REPLACEMENT. 2. GOVERNOR GEAR IS WORN IN THE MODDLE, BUT ON ONE SIDE ONLY. (SEE FIGURE 2). CAUSE: 1. THE GOVERNOR DOWEL PIN IS LOCATED TOO FAR INTO ITS CASE BORE. REFER TO FIGURE 3 FOR CORRECT DIMENSION.) 2. GOVERNOR SLEEVE STUCK IN CASE BORE. 3. THE OUTPUT SHAFT TO INPUT CARRIER SNAP RING IS LOOSE OR HAS COME OFF. THE OUTPUT SHAFT HAS MOVED REARWARD. CORRECTION: 1. REPLACE THE TRANSMISSION CASE. CHECK REPLACEMENT CASE FOR CORRECT DIMENSION. 2. REPLACE GOVERNOR ASSEMBLY AND TRANSMISSION CASE. 3. DISASSEMBLE THE TRANSMISSION, REPLACE THE OUTPUT SHAFT TO INPUT CARRIER SNAP RING (P/N 8642230). 3. GOVERNOR GEAR IS WORN AT THE EDGE OF THE GEAR ON ONE SIDE ONLY (REFER TO FIGURE 4). CAUSE: 1. THE GOVERNOR DOWEL PIN IS LOCATED TOO FAR OUT OF ITS CASE BORE. (SEE FIGURE 3 FOR CORRECT DIMENSION). CORRECTION: 1. ARBOR PRESS THE DOWEL PIN INTO THE CASE TO THE CORRECT DIMENSION (REFER TO FIGURE 3.) 4. GOVERNOR GEAR IS WORN SLIGHTLY, THE ENTIRE LENGTH OF THE GEAR. (SEE FIGURE 5). CAUSE: 1. THE INCORRECT GOVERNOR GEAR WAS INSTALLED. CORRECTION: 1. REPLACE THE GOVERNOR GEAR (P/N 8642928) -- DO NOT -- USE A THM 350-C GEAR AS A REPLACEMENT GEAR.

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.