INSTRUMENT CLUSTER SERVICE EXCHANGE PROCEDURE OUTLINED. GMC Truck GMC K Pickup

VEHICLES AFFECTED: 1988 C/K TRUCKS

The 1988 C/K instrument clusters will be serviced on an exchange only basis until July 1, 1987.

To obtain a remanufactured cluster, contact the authorized AC Delco Exchange Center listed below. Provide the VIN, vehicle mileage, and whether the cluster is the standard or deluxe (with gages) cluster. A core charge will be attached to the cluster, which will be removed when the malfunctioning cluster is returned.

The remanufactured cluster will have the odometer set to the mileage provided, but the speedometer will not be calibrated. Correct speedometer calibration is necessary for an input signal to the rear wheel antilock (RWAL) controller and is affected by tire siz 'e and axle ratio. The speedometer calibration chart is on Page 5A3-24 of the 1988 C/K Service Manual. A calibration clip will be provided with the exchange cluster. Follow the speedometer calibration procedure, Steps 3-6 only, Section 5A3-22, of the 1988 C/K Service Manual. Steps 1 and 2 have been performed by the authorized AC Delco Exchange Center.

Notice: Because of the presence of the rear wheel antilock brake system, locally performed changes to tire size And/or rear axle ratio must be programmed into the speedometer. Separate programming bars will be available from GM Parts within the next few months. A bulletin detailing this information and programming procedures will be released when the parts become available.

Notice: The only speedometer parts currently available through GM Parts are the two cluster lenses.

Part Number 25079967 - base cluster lens Part Number 25079682 - cluster lens (with gages)

Custone Auto Radio 1614 Charles Street Whitby, Ontario Canada LIN IB9

(1-800-263-2691)

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.