RAM 2500 Truck 4WD V10-8.0L VIN W HDC (2000)
Brake Switch (Cruise Control): Description and Operation
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 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.
