C 2500 Truck 2WD V8-350 5.7L (1988)
Brake Lamp: Customer Interest
Lighting - Brake Lights Stay ON
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.
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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.
