CLEARING 4WAL TROUBLE CODES SERVICE PROCEDURES/INFORMATION

SUBJECT: CLEARING RWAL/4WALTROUBLE CODES

MODELS: ALL 1990-91 M/L VANS AND S/T 4 DOOR UTILITY VEHICLES EQUIPPED WITH FOUR WHEEL ANTILOCK (4WAL) BRAKE SYSTEMS

Some technicians may experience difficulty in clearing stored codes when using the Tech One scan tool after repairs have been performed on 4WAL systems. If this occurs the ignition should be cycled off for 5 seconds and then technicians should attempt to clear the code(s) again. It may be necessary to cycle the ignition in this manner several times before the codes will clear. Once cleared, a function test of the system along with a road test should be made to verify that the repair was made correctly and the codes do not RESET Note: Use of the Tech One tool is highly recommended (refer to GMC Truck Service Bulletin 91-5E-74; Corporate Number 166003).

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.