Durango 2WD V8-5.2L VIN Y (1999)
Brake Light Switch: Description and Operation
With Antilock Brakes
The primary function of the switch is to turn on the stop lamps during braking. The switch is also used to send signals to components that must know
when the brakes are applied, such as the Powertrain Control Module (PCM), which uses the signal to cancel speed control. The CAB uses the brake
switch signal to monitor brake pedal application. When the switch contacts open (brakes applied), the CAB receives the brake applied signal. The
CAB then monitors the RWAL system to anticipate the need for an RWAL stop.
When the brake light switch is activated, the Powertrain Control Module (PCM) receives an input indicating that the brakes are being applied. After
receiving this input, the PCM maintains idle speed to a scheduled rpm through control of the Idle Air Control (IAC) motor. The brake switch input is
also used to disable vent and vacuum solenoid output signals to the speed control servo.
