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:

C2-C5:

Normal Operation

NOTE: Tapping the brake pedal deactivates the speed control. It is necessary to apply the brakes in order to slow the vehicle down.

The speed control actuator sends a voltage reference signal through circuit 511 (LG). 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 SJB to the speed control deactivator switch through circuits 101 (GY/YE) and 998 (YE/LG). The speed control deactivator switch (closed when the brake pedal is not applied) then routes the voltage to circuit 248 (TN/OG) and then to circuit 810 (RD/LG) to the speed control actuator. When the brake pedal is firmly pressed, 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 248 (TN/OG) shorted to voltage
- circuit 511 (LG) open
- circuit 810 (RD/LG) shorted to voltage
- speed control deactivator switch
- stoplamp switch
- speed control cable
- accelerator cable
- speed control actuator