For 1990-2009 cars

# ABS ACTIVATION DURING BRAKING ON ROUGH OR WASHBOARD SURFACE

#### SUBJECT: ABS ACTIVATION DURING BRAKING ON ROUGH ROADS (DIAGNOSIS)

#### VEHICLES AFFECTED: 1990-1991 D MODEL, 1991 E, K, MODEL

On 1990-1991 Broughams and 1991 Eldorados and Sevilles the ABS may activate during brake application while driving on rough or washboard-type surfaced roads. This is a normal condition.

During braking on a rough road it is possible for one or more wheels to leave the road surface. When this occurs, the ABS Electronic Brake Control Module (EBCM) interprets the airborne wheel as locking up. The EBCM will subsequently initialize ABS and reduce brake line pressure to the wheels that are locking. This is a calculated response.

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.