GM S10/S15/Sonoma Pick-Ups 1982-1993 Repair Manual

Brake Light Switch


A brake light switch is mounted to the pedal bracket on all vehicles covered by this manual. The purpose of the switch is to illuminate the brake lights whenever the pedal is depressed, therefore proper operation and adjustment is critical to safe vehicle operation. All switches are normally mounted using an interference clip. The clip holds ribs located on the switch's neck. The ribbed switch is self-adjusting when installed properly.


See Figure 1

  1. Disconnect the negative battery cable.
  3. Disengage the vacuum and/or electrical connector(s) from the switch.

Some brake light switches may be combined with the cruise control release switch, therefore may contain a vacuum hose or an additional electrical connector. If so, be sure to tag all hoses/wiring before disconnecting in order to assure proper installation.

Click image to see an enlarged view

Fig. Fig. 1: Common brake light switch mounting

  1. Grasp the switch and withdraw it from the clip. If necessary the clip can be removed from the pedal bracket as well. Some clips are designed with lock tangs and may be pivoted in order to pull them from the bracket. On these, you may twist the switch and retainer clip together and withdraw them as an assembly. Other clips are also an interference fit and must be squeezed and withdrawn.

To install:
  1. If removed, install the retainer to the pedal bracket.
  3. With the pedal depressed so it will not interfere, insert and fully seat the switch into the clip on the pedal bracket.
  5. In order to adjust the switch, grasp the pedal and pull it fully back against the stop. While pulling the pedal backwards, a clicking sound should be heard as the switch is pushed backwards in the clip until it is in the proper position. Make sure the switch plunger is seated when the pedal is released and that the plunger fully extends as the pedal is depressed. Check the switch operation and adjust again, if necessary.
  7. Engage the vacuum line and/or electrical connector(s) to the switch.
  9. Connect the negative battery cable.
  11. Verify proper switch operation.


Most vehicles covered by this manual utilize a self-adjusting brake light switch which is mounted to an interference clip on the pedal bracket. If adjustment becomes necessary on interference clip switches, check to be sure the retaining clip and switch ribs are not worn or damaged, then replace, if necessary. If no damage is found, adjust the switch:

  1. Depress the brake pedal and press the brake light switch inward until it seats firmly against the clip.

As the switch is being pushed into the clip, audible clicks can be heard.

  1. Release the brake pedal, then pull it back against the pedal stop until the audible clicks can no longer be heard. The clicks indicate that the switch is moving into position in the clip for proper adjustment.
  3. Verify that the switch operates properly when the pedal is depressed and released.