SURGE WHEN TCC ENGAGES NEW PROM P/N TO REVISE TCC

Model and Year: 1985-86 CELEBRITY MODELS WITH LR8 2.5L ENGINES (VIN CODE R) MD9 3-SPEED AUTOMATIC TRANSMISSION AND F17 (2.84 RATIO) OR F62 (2.39 RATIO) TRANSAXLE

TO: ALL CHEVROLET DEALERS

Customer comments of "chuggle" or "surge" may be received on 1985-86 Celebrity models with 2.5L L4 engines when the torque converter clutch (TCC) engages at lower vehicle speeds.

This condition will be improved by the installation of a new service PROM. These service PROMS contain calibration changes designed to enhance vehicle driveability. The TCC engagement speed will be raised to 49 mph. Service PROM applications are listed below:

PROM P/N APPLICATION -------- ----------- 1228020 1985 Celebrity with 2.84 axle 1227924 1985 Celebrity with 2.39 axle

1228019 1986 Celebrity with 2.84 axle 1228018 1986 Celebrity with 2.39 axle

Use applicable Labor Time and Operation numbers.

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.