NO DRIVE OR HARSH SHIFT DIAGNOSIS 125 TRANSMISSION

When diagnosing any 125 or 125C transmission for no drive or harsh shifts (high line pressure), check the control valve assembly for a worn or missing pressure regulator valve retaining pin (see Figure 1 for pin location).

If the pressure regulator valve retaining pin is worn or missing, perform the following repair:

(1) Position the control valve and oil pump assembly with the machined portion face down. Be certain the machined face is protected to prevent nicks, burrs, scratches, etc. Completely disassemble pressure regulator valve as shown in Figure 2.

(2) Use a 3/8 drift punch and hammer to stake (close) the pressure regulator valve retaining pin hole. See insert Figure 1. Stake the pin hole only enough to hold the new retaining pin in place after assembly.

(3) Reassemble the pressure regulator and reverse boost valve train assembly (see Figure 2).

(4) Retain the valve train with a new steel retaining pin, P/N 112496. The new pin must be inserted from and flush with the machined face of the control valve and oil pump assembly.

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.