SECOND GEAR STARTS CHECK 1-2 SHIFT VALVE

MODELS AFFECTED: 1984-1987 THM 440-T4 (ME9)

BULLETIN COVERS

A 1984-1987 vehicle equipped with a THM 440-T4 (Figure 1) may start out in 2nd gear instead of 1st gear. This candition could occur intermittently or all the time.

SERVICE ACTION

High line pressure could be a cause by holding too much governor pressure and not allowing the 1-2 shift valve to downshift. Check line pressure and governor pressure. Governor pressure should be below 3.0 psi at 0 mph.

If the governor pressure is okay, the 1-2 shift valve (331) may be stuck in the upshifted position. Remove the control valve assembly and check for a sticking 1-2 shift valve (331), 1-2 throttle valve (332), or the 1-2 throttle valve spring (333) caused by the 1-2 throttle valve bushing retainer (390) pushed in too far, The retainer should be installed flush with the machined surface of the valve body (Figure 2).

SERVICE MANUAL REFERENCE

Refer to the THM 440-T4 (ME9) Automatic Transaxle Unit Repair Section in the appropriate Service Manual.

SERVICE NOTES

For 1985 CP, CW or HT THM 440-T4 transaxle models, refer to Corporate Bulletin 857610.

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.