Test C: The Speed Control Does Not Disengage When the Brakes Are Applied

PINPOINT TEST C: THE SPEED CONTROL DOES NOT DISENGAGE WHEN THE BRAKES ARE APPLIED

C1-C3:

C3-C4:

Normal Operation
The speed control actuator sends a voltage reference signal through circuit 306 (TN/LB). The stoplamps provide a ground path that enables speed control operation. When the brake pedal is applied, the voltage goes high and speed control goes into standby mode.

Voltage for the speed control servo clutch (internal to the speed control actuator) is supplied by the smart junction box (SJB) to the speed control deactivator switch through circuit 535 (LB/RD). The speed control deactivator switch (closed when the brake pedal is not applied) then routes the voltage to circuit 307 (BK/YE) to the speed control actuator. When the brake pedal is firmly applied, the speed control deactivator switch opens and voltage is no longer supplied to the speed control servo clutch.

Possible Causes
- Obstructions to the accelerator pedal or linkage
- Circuit 307 (BK/YE) short to voltage
- Circuit 306 (TN/LB) open
- Speed control deactivator switch
- Stoplamp switch
- Speed control cable
- Accelerator cable
- Speed control actuator