BRAKE LIGHTS STAY ON DIAGNOSIS/REPAIR DESCRIBED

VEHICLES AFFECTED: 1988 C/K TRUCKS

On some 1988 C/K model trucks the brake lights have been found to stay on after the brake pedal has been released. In a majority of cases, the stoplamp switch being misadjusted has been the cause. Other possible causes include the following:

A binding condition between the eyelet of the brake booster rod and its attachment pin at the pedal.

Pedal mounting bushings not being properly lubricated.

Whenever the stop lights remain on after the pedal has been released the stoplamp switch should be correctly adjusted.

The 1988 C/K Service Manual, X-8731, is unclear and inaccurate in providing information on stoplamp switch adjustment. Revised switch adjustment procedures are given below. In all cases, before a stoplamp switch is replaced for the subject condition, it should be adjusted and tested on the vehicle to determine if it is defective.

SERVICE PROCEDURE

Switch Adjustment

Start engine.

Depress brake pedal fully.

Pull lever (A) rearward (toward back of vehicle) to its stop (Figure No. 1).

Release brake pedal.

Switch Replacement

Disconnect the negative battery cable. Remove switch. Disconnect electrical connectors. Install new switch. - Reconnect electrical connectors. - Install clamp 'C' around brake pedal arm. - Slide switch upward with slide tabs 'D' engaged in brake pedal bracket slot and upper clamp 'B' aligned with pedal hub. Reconnect negative battery cable. Adjust switch. Refer to 'Switch Adjustment'.

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.