NO UPSHIFT AFTER A PART OR FULL THROTTLE DETENT

MOOELS AFFECTED: 1984-1985 BROUGHAM, 1984-1985 ELDORADO/SEVILLE EQUIPPED WITH GAS ENGINES

Some 1984-1985 Cadillacs equipped with gasoline engines and either a THM200-4R or THM325-4L automatic transmission may experience a no upshift condition after a wide-open throttle (WOT) detent downshift. This condition is due to excessive hydraulic assist acting on the throttle valve (TV) plunger and bushing. This assist is used to reduce throttle pedal effort. The no shift condition can be intermittent and will normally be eliminated after shutting the engine off. A revised Throttle Valve plunger and bushing P/N 8639937, which uses a larger plunger stem to reduce hydraulic assist, has been released for service.

When servicing an automatic transmission for this condition, first verify the TV Cable condition, adjustment and routing as outlined in the appropriate Service Information Manual. If no problem is found, install a service TV plunger and bushing assembly using the service procedure and parts information listed below.

SERVICE INFORMATION

1. Remove the transmission oil pan, remove all pan gasket or sealing material.

2. Remove the TV cable from the TV linkage. Remove the TV linkage from the control valve body assembly. Do not remove the control valve body assembly.

3. Remove the roll-pin used to retain the TV plunger and bushing into the control valve body assembly. Remove and replace the TV plunger and bushing (refer to Figures 1 and 2) with service kit part number 8639937) and reinstall the retaining roll-pin. If servicing a 1984 THM200-4R, produced prior to April 25, 1984 (Julian date 116, refer to Figure 3), replace the control valve body with part number 8639342 (as detailed in Serviceman Bulletin T85-38). Be sure to install the revised TV plunger and bushing listed below into the replacement control valve body prior to reassembly.

4. Re-install the TV cable and linkage. Install the transmission oil pan and fill with transmission fluid to the proper level as described in the appropriate Service Information Manual (SIM).

5. Adjust the TV cable per procedure listed in the appropriate SIM.

6. Road test to verify proper upshift and downshift performance.

WARRANTY INFORMATION

When replacing the TV plunger and bushing on either a THM 200-4R or THM 325-4L use labor Operation number T6143 at .8 hours.

When replacing the control vlave assembly and the TV plunger and bushing on a 1984 THM 200-4R use labor operation number K6560 for .9 hours.

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.