Scheme 1
Scheme 2
Scheme 3
Principles of Operation
The brake pedal position (BPP) switch is normally closed to ground. When the brake pedal is applied with the speed control system engaged, the BPP switch closes (to battery voltage), putting the speed control in stand-by mode.
Note. A redundant brake deactivator (BPA) switch is provided as an additional safety feature.
Note. The speed control module is integral to the powertrain control module (PCM).
The clockspring provides the electrical interface between the steering column wiring and the speed control switches in the steering wheel.
The inputs to the powertrain control module (PCM) required to operate the speed control system are the
- anti-lock brake (ABS) module
- digital transmission range (TR) sensor
- speed control deactivator switch
- speed control switches
- vehicle speed signal (VSS)
The inputs to the speed control actuator come from the powertrain control module (PCM).
The outputs of the speed control actuator go to the speed control cable controlled throttle position sensor.
Normal Operation
Under normal operation the powertrain control module (PCM) sends a signal, through circuit 151 (LB/BK) to the speed control switches which passes through the clockspring. The return signal is sent through circuit 848 (DG/OG) and the clockspring.
Under normal operation the powertrain control module (PCM) sends a signal through circuit 151 LB/BK) to the speed control switches which passes through the clockspring. The return signal is sent through circuit 848 (DG/OG) and the clockspring.
Under normal operation, when the powertrain control module (PCM) senses battery voltage on circuit 810 (RD/LG), the PCM deactivates the speed control actuator. Additionally, when the brake pedals pressed and the speed control deactivator switch pens, battery voltage is removed from circuit 307 (BK/YE) to the speed control actuator or the PCM, releasing the throttle independently of the speed control actuator.
Under normal operation the powertrain control module (PCM) sends signals to the speed control actuator which receives the signals and adjusts the step-up motor inside the speed control actuator depending on the various inputs it has received.
When the brake pedal is applied, the powertrain control module (PCM) will receive battery voltage from the brake pedal position (BPP) switch, deactivating the speed control system. A speed control deactivator switch opens when the brake is applied, deactivating the speed control.
The digital transmission range (TR) sensor enables the speed control switches to send signals to the powertrain control module (PCM) inputs for the speed control system. The PCM interprets the signals and then outputs them to the speed control actuator then pulls the cable to the correct position enabling the speed control to be set. When the brake pedal is pressed the brake pedal position (BPP) switch and the brake pressure applied (BPA) switch and the brake pressure applied (BPA) switch will in turn deactivate the speed control system.
Under normal operation the instrument cluster receives a signal from the powertrain control module (PCM) to indicate that the speed control system is activated.
See also:
• SELF-DIAGNOSTICS - CNG, FLEX-FUEL & GASOLINE