SWITCH, Stop Lamp - 2012 Jeep Wrangler JK Factory Service Manual

DESCRIPTION

The brake lamp switch (1) is a three circuit, spring-loaded plunger actuated switch that is secured to a stamped metal brake lamp switch bracket on the instrument panel structural support armature near the brake pedal 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 instrument panel 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 the brake pedal moving 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 (or stop) 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 an ignition run/start control output circuit, and supplies this battery voltage to the PCM on a brake signal 2 circuit only when the brake pedal is released (brake lamp switch plunger is depressed).

The PCM sends electronic brake lamp switch status messages to other electronic modules in the vehicle over the Controller Area Network (CAN) data bus for use as an additional logic input for controlling many other vehicle functions and features.

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. However, conventional diagnostic methods will not prove conclusive in the diagnosis of the electronic controls and communication that provide some features related to brake lamp switch operation. The most reliable, efficient and accurate means to diagnose the electronic controls and communication related to brake lamp switch operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.

DIAGNOSIS AND TESTING - STOP LAMP SWITCH

WARNING:

To avoid serious or fatal injury on vehicles equipped with airbags, disable the Supplemental Restraint System (SRS) 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 SRS. Failure to take the proper precautions could result in accidental airbag deployment.

Disconnect and isolate the battery negative cable.

Disconnect the wire harness connector from the brake lamp switch.

Using an ohmmeter, perform the continuity tests at the terminal pins (1) in the brake lamp switch connector receptacle as shown in the Brake Lamp Switch Tests table.

BRAKE LAMP SWITCH TESTS
PLUNGER POSITION (2)	CONTINUITY BETWEEN
Released (Extended)	Pins 1 and 2
Compressed (Depressed)	Pins 3 and 4, 5 and 6

If the switch fails any of the continuity tests, replace the ineffective brake lamp switch as required.

ADJUSTMENT

WARNING:

To avoid serious or fatal injury on vehicles equipped with airbags, disable the Supplemental Restraint System (SRS) 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 SRS. Failure to take the proper precautions could result in accidental airbag deployment.

Disconnect and isolate the battery negative cable.

Remove the steering column opening cover from the instrument panel. (Refer to 23 - Body/Instrument Panel/COVER, Steering Column Opening - Removal) .

Depress and hold the brake pedal in the depressed position.

Pull the brake lamp switch plunger all the way out of the switch housing to its fully extended position.

Release the brake pedal. 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.

Reinstall the steering column opening cover onto the instrument panel. (Refer to 23 - Body/Instrument Panel/COVER, Steering Column Opening - Installation) .

Reconnect the battery negative cable.

REMOVAL

WARNING:

To avoid serious or fatal injury on vehicles equipped with airbags, disable the Supplemental Restraint System (SRS) 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 SRS. Failure to take the proper precautions could result in accidental airbag deployment.

Disconnect and isolate the battery negative cable.

Remove the steering column opening cover from the instrument panel (2). (Refer to 23 - Body/Instrument Panel/COVER, Steering Column Opening - Removal) .

Depress and hold the brake pedal in the depressed position.

Rotate the brake lamp switch housing (4) counterclockwise about 30 degrees to align the tabs on the switch locking collar with the keyed hole in the brake lamp switch mounting bracket (3).

Pull the switch straight back from the keyed hole to remove it from the bracket.

Release the brake pedal.

Disconnect the wire harness connector (1) from the brake lamp switch.

INSTALLATION

WARNING:

To avoid serious or fatal injury on vehicles equipped with airbags, disable the Supplemental Restraint System (SRS) 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 SRS. Failure to take the proper precautions could result in accidental airbag deployment.

Be certain that the brake lamp switch (4) plunger is pulled all the way out of the switch housing to its fully extended position.

Reconnect the wire harness connector (1) to the connector receptacle on the switch.

Depress and hold the brake pedal in the depressed position.

Align the tabs on the brake lamp switch locking collar with the keyed hole in the brake lamp switch mounting bracket (3).

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.

Rotate the switch housing clockwise about 30 degrees to engage the tabs on the locking collar with the mounting bracket.

Release the brake pedal. 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.

Reinstall the steering column opening cover onto the instrument panel (2). (Refer to 23 - Body/Instrument Panel/COVER, Steering Column Opening - Installation) .

Reconnect the battery negative cable.