For 1990-2009 cars

# ABS PEDAL PULSATION NEW WHEEL SPEED SENSOR

#### SUBJECT: ABS BRAKE PEDAL PULSATION WHEN APPLYING BRAKES-NEW WHEEL SPEED SENSOR

#### MODELS/YEARS: 1991-92 EIGHTY EIGHT AND NINETY EIGHT WITH JM4 OPTION

This bulletin cancels and supersedes Dealer Technical Bulletin 91-T-145 which should be discarded.

#### CONDITION:

---------- Owners may notice brake pedal vibration (ABS cycling) and the pedal may drop approximately one inch at the end of a brake stop. This usually happens when decelerating below 10 mph and the brakes are not applied hard enough and road conditions are not such to activate the Antilock System.

#### CAUSE:

------ This condition may be caused by moisture intrusion into the rear wheel speed sensor.

#### DIAGNOSIS AND CORRECTION:

The pedal vibration (ABS cycling) due to moisture intrusion may or may not set a trouble code. Use a Tech I or CAMS to read any trouble codes that may be stored in the EBCM. Follow the service manual procedure to repair any stored codes.

If any of the rear wheel speed sensor codes are stored or if no trouble codes are stored, replace both rear wheel speed sensors with P/N 10457166 (one per box), clear codes, and road test the vehicle before replacing any other Antilock System Component. This new sensor can be identified from previous (grey) sensor by the BLACK color.

Parts are currently available from GMSPO.

#### WARRANTY INFORMATION:

Use the current Labor Time Guide.

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.