HARSH NEUTRAL TO REVERSE/DRIVE CHECK VACUUM LINE FOR BLOCKAGE

MODELS AFFECTED: 1984-87 CENTURYS, ELECTRAS, LESABRES AND RIVIERAS EQUIPPED WITH 3.8L V-6 ENGINES (VIN CODES B & 3) AND THM 440-T4 TRANSAXLE

Some THM 440-T4 transaxles may exhibit harsh Neutral to Reverse, Neutral to Drive, Park to Reverse, Park to Drive, and/or transmission slippage. These conditions may be caused by a plugged vacuum tube from the engine to the transmission modulator.

When servicing any THM 440-T4 for this condition, remove the vacuum tube and inspect for any obstructions. Especially check for a thin coat of paint at the engine end of the pipe. Remove any foreign material so that the inner diameter of the pipe is completely open. This should be done prior to any disassembly of the transmission for corrective repairs.

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.