SWITCH-STOP LAMP
DESCRIPTION
The brake lamp switch (1) is a three circuit, spring-loaded plunger actuated switch that is secured to the brake pedal support bracket under the instrument panel on the driver side of the vehicle. The molded plastic switch housing has an integral connector receptacle (4) containing six terminal pins. The switch is connected to the vehicle electrical system through a dedicated take out of the headlamp and dash wire harness.
The switch plunger (3) extends through a mounting collar (2) on one end of the switch housing. The plunger has a telescoping self-adjustment feature that is activated after the switch is installed by pulling the brake pedal upward to its normal at-rest position. The telescoping plunger can be pulled outward from the switch housing to repeat the self-adjustment procedure if necessary.
The brake lamp switch cannot be repaired. If the switch is damaged or ineffective it must be replaced with a new unit.
OPERATION
The brake lamp switch controls three independent circuits. These circuits are described as follows:
- Brake Lamp Switch Circuit - A normally open brake lamp switch circuit receives a battery voltage input, and supplies this battery voltage to the brake lamps and the Controller Antilock Brake (CAB) on a brake lamp switch output circuit only when the brake pedal is depressed (brake lamp switch plunger released).
- Brake Lamp Switch Signal Circuit - A normally closed brake lamp switch signal circuit receives a direct path to ground, and supplies this ground input to the Powertrain Control Module (PCM) on a brake lamp switch sense circuit only when the brake pedal is released (brake lamp switch plunger is depressed).
- Speed Control Circuit - A normally closed speed control circuit receives a battery voltage input from the PCM on a speed control supply circuit, and supplies this battery voltage to the speed control servo solenoids (dump, vacuum, and vent) on a speed control brake switch output circuit only when the speed control system is turned ON and the brake pedal is released (brake lamp switch plunger is depressed).
The brake lamp switch as well as the hard wired inputs and outputs of the switch may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information.
REMOVAL
WARNING: To avoid personal injury or death, on vehicles equipped with airbags, disable the supplemental restraint system before attempting any steering wheel, steering column, airbag, seat belt tensioner, impact sensor, or instrument panel component diagnosis or service. Disconnect and isolate the battery negative (ground) cable, then wait two minutes for the system capacitor to discharge before performing further diagnosis or service. This is the only sure way to disable the supplemental restraint system. Failure to take the proper precautions could result in accidental airbag deployment.
1. Disconnect and isolate the battery negative cable.
2. Remove the steering column opening cover from the instrument panel. (Refer to 23 - BODY/INSTRUMENT PANEL/STEERING COLUMN OPENING COVER - REMOVAL).
3. Depress and hold the brake pedal in the depressed position.
4. Rotate the brake lamp switch housing (3) counterclockwise about 30 degrees to align the tabs on the switch locking collar with the keyed hole in the brake pedal mounting bracket (2).
5. Pull the switch straight back from the keyed hole to remove it from the bracket.
6. Release the brake pedal.
7. Disconnect the wire harness connector (1) from the brake lamp switch.
INSTALLATION
WARNING: To avoid personal injury or death, on vehicles equipped with airbags, disable the supplemental restraint system before attempting any steering wheel, steering column, airbag, seat belt tensioner, impact sensor, or instrument panel component diagnosis or service. Disconnect and isolate the battery negative (ground) cable, then wait two minutes for the system capacitor to discharge before performing further diagnosis or service. This is the only sure way to disable the supplemental restraint system. Failure to take the proper precautions could result in accidental airbag deployment.
1. Be certain that the brake lamp switch (3) plunger is pulled all the way out of the switch housing to its fully extended position.
2. Reconnect the wire harness connector (1) to the connector receptacle on the switch.
3. Depress and hold the brake pedal in the depressed position.
4. Align the tabs on the brake lamp switch locking collar with the keyed hole in the brake pedal mounting bracket (2).
5. Insert the tab on the brake lamp switch locking collar through the keyed hole in the mounting bracket until the switch housing is firmly seated against the bracket.
6. Rotate the switch housing clockwise about 30 degrees to engage the tabs on the locking collar with the mounting bracket.
CAUTION: Brake booster damage may occur if the brake pedal pull exceeds about 9 kilograms (20 pounds).
7. Release the brake pedal. Then pull the pedal lightly upward to its normal at-rest position. The pedal will set the plunger to the correct position as the pedal pushes the plunger into the switch housing. The switch plunger will make a light audible ratcheting noise as it self-adjusts.
8. Reinstall the steering column opening cover onto the instrument panel. (Refer to 23 - BODY/INSTRUMENT PANEL/STEERING COLUMN OPENING COVER - INSTALLATION).
9. Reconnect the battery negative cable.