Replace the brake light switch, which activates the brake lights when the brake pedal is depressed. This is a safety-critical component that ensures following vehicles are warned when you are braking.

Warnings

Tools required

Parts

• Brake light switch × 1 — Use OEM specification or Standard Motor Products SLS-24

Preparation

1. Park vehicle on level ground and set parking brake
2. Disconnect negative battery terminal to prevent electrical shorts
3. Allow engine to cool completely if recently driven
4. Position yourself comfortably to access area under dashboard above brake pedal
5. Have flashlight ready to illuminate work area

Procedure

1. 1

   Locate the brake light switch
   Position yourself under the dashboard on the driver's side. Look above the brake pedal arm near the pivot point. The brake light switch is mounted on a bracket and connects to the brake pedal pushrod or pedal arm. It has a threaded body with a locknut and two wire terminals.
2. 2

   Disconnect electrical connector
   Identify the two-wire electrical connector on the brake light switch. Note the wire colors and positions for proper reinstallation. Carefully pull the connector terminals off the switch. On some variants, there may be a small clip connector that slides off. If terminals are corroded, spray with electrical contact cleaner.
3. 3

   Loosen the switch locknut
   Using an adjustable wrench or 7/16" wrench, hold the brake light switch body to prevent it from turning. With another wrench, loosen the locknut that secures the switch position. The locknut is typically located between the switch body and the mounting bracket. Turn counterclockwise to loosen.
4. 4

   Remove the old switch
   Once the locknut is loose, unscrew the brake light switch from the mounting bracket by turning it counterclockwise. Count the number of turns as you remove it to aid in installation of the new switch. The switch may have a spring-loaded plunger that contacts the brake pedal arm. Carefully extract the switch from the confined space.
5. 5

   Prepare the new switch
   Compare the new brake light switch to the old one to verify correct replacement part. Check that threads are clean and undamaged. Thread the locknut onto the new switch body before installation. If the switch has an adjustable plunger, set it to approximately the same position as the old switch.
6. 6

   Install the new switch
   Thread the new brake light switch into the mounting bracket, turning clockwise. Install it to approximately the same depth as the old switch was removed (use the turn count from removal). The switch plunger should contact the brake pedal arm when the pedal is released, and should disengage when the pedal is depressed approximately 1/4 to 1/2 inch.
7. 7

   Adjust switch position
   With the brake pedal in the fully released position, adjust the switch so the plunger is compressed approximately 1/16" to 1/8". This ensures the brake lights are OFF when the pedal is released and activate immediately when the pedal is pressed. The switch should click audibly when the circuit opens and closes.
8. 8

   Tighten the locknut
   While holding the brake light switch body in position with one wrench, tighten the locknut against the mounting bracket with the other wrench. Tighten firmly to prevent the switch from rotating or changing position during pedal operation, but do not overtighten as this can crack the switch housing.
9. 9

   Reconnect electrical connector
   Reconnect the wire terminals to the brake light switch in the same positions as removed. Ensure the terminals are fully seated and make good contact with the switch posts. Gently tug on the wires to verify connections are secure.
10. 10

    Reconnect battery and test
    Reconnect the negative battery terminal. Turn the ignition to the ON position (engine does not need to run). Have an assistant observe the rear brake lights, or position a mirror or reflective surface behind the vehicle. Press the brake pedal and verify both brake lights illuminate. Release the pedal and verify lights turn off completely.

Reassembly

1. No disassembly was required beyond component removal
2. Ensure all electrical connections are secure and properly routed away from moving brake pedal components
3. Verify locknut remains tight after several brake pedal applications

Verification

• With ignition ON, press brake pedal and verify both brake lights illuminate immediately
• Release brake pedal completely and verify both brake lights turn OFF
• Press brake pedal multiple times while watching brake lights to confirm consistent operation
• Check that brake lights remain OFF when vehicle is parked with engine off
• Test cruise control if equipped, as it may share the brake switch circuit for disengagement
• Road test vehicle in safe area and verify brake lights function normally before returning to regular service
• Have another person verify brake lights or use a reflective surface for final confirmation

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