SECOND GEAR STARTS THM-440-T4 TRANSAXLE

MODEL AND YEAR: 1984-87 CELEBRITY WITH THM 440-T4 TRANSAXLE

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

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 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 NOTES:

For 1985 CP, CW or HT THM 440-T4 transaxle models, refer to Chevrolet Dealer Service Bulletin 85-122 (Section 7A) dated Sept., 1985.

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.