Jeep Cherokee
 Service Manual
Speed control system » Description and operation
Brake lamp switch


The switch is mounted on the brake pedal mounting bracket under the instrument panel.


Vehicles equipped with the speed control option use a dual function brake lamp switch. The PCM monitors the state of the dual function brake lamp switch.

Refer to the Brake section for more information on brake lamp switch service and adjustment procedures.

The brake switch is equipped with three sets of contacts, one normally open and the other two normally closed (brakes disengaged). The PCM sends a 12 volt signal to one of the normally closed contacts in the brake switch, which is returned to the PCM as a brake switch state signal. With the contacts closed, the 12 volt signal is pulled to ground causing the signal to go low. The low voltage signal, monitored by the PCM, indicates that the brakes are not applied.

When the brakes are applied, the contacts open, causing the PCM's output brake signal to go high, disengaging the speed control, cutting off PCM power to the speed control solenoids.

The second set of normally closed contacts supplies 12 volts from the PCM any time speed control is turned on. Through the brake switch, current is routed to the speed control servo solenoids. The speed control solenoids (vacuum, vent and dump) are provided this current any time the speed control is ON and the brakes are disengaged.

When the driver applies the brakes, the contacts open and current is interrupted to the solenoids. The normally open contacts are fed battery voltage. When the brakes are applied, battery voltage is supplied to the brake lamps.

    More about «Description and operation»:

    Speed control system

    Speed control servo

    Speed control solenoid circuits

    Speed control switches

    Brake lamp switch

    Servo cable

    Vacuum reservoir

    Vehicle speed sensor (speed control operation)

    Jeep Cherokee Service Manual / Speed control system / Description and operation / Brake lamp switch

    Jeep Cherokee Service Manual


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