Brakes - Pedal Pulsation When Applied

91oldsmobile04

NUMBER: 91-T-145

CORP.REF.NO.: 105002R

DATE: June 1991

SECTION: 5E


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


MODELS/YEARS 1991 EIGHTY-EIGHT, NINETY-EIGHT


CONDITION: Owners may notice a pulsation (ABS cycling) feel in the brake pedal when braking. This usually happens when decelerating below 10 mph and brakes are not applied hard enough to activate the Antilock System. Ninety-Eight models built prior to vehicle number M4323397 and Eighty-Eight models built prior to vehicle numbers MH337401 or M1814577, may exhibit this condition.

CAUSE: This may be caused by moisture intrusion into the rear wheel speed sensor.

DIAGNOSIS AND CORRECTION: Pedal pulsation due to moisture intrusion may or may not set a trouble code. Install a Tech 1 scan tool to read any trouble codes that are stored and follow the diagnostic charts in the service manual.

If no trouble codes are stored, replace both rear wheel speed sensors.

REPLACEMENT PARTS: A new wheel speed sensor, P/N 10456499 (1 per box) has been released for service. Parts are currently available from GMSPO.