FOUR WHEEL ANTI-LOCK (4WAL) CODE 65 MISDIAGNOSIS

VEHICLES AFFECTED: 1990 L AND M VANS

The instrument panel (I.P.) anti-lock warning light will only come on when an abnormal condition exists within the 4WAL system. It should be noted that if the I.P. anti-lock warning light is not on, it can accidentally be turned on and remain on by grounding diagnostic terminal "H" to "A" twice within ten seconds. If this occurs, and Code 65 is read out using the diagnostic procedure, then this code was probably set by the technician. This is a peculiarity within the 4WAL system, and should not be interpreted as a faulty condition. Technicians who have accidentally induced a Code 65 in this manner should simply clear the code prior to returning the vehicle to the customer.

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.