Lighting - Brake Lights Stay ON

87chevy19
GMC NUMBER: 88-T-48

GROUP: 5-Brakes

DATE: October, 1987

CORPORATE
NUMBER: 865003
SUBJECT: BRAKE LIGHTS STAY ON

MODELS: 1988 C/K MODELS
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.

FIGURE NO. 1 - STOPLAMP SWITCH:

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".