Cruise Control Module: Description and Operation

The cruise control module is located on the left side of instrument panel. The main function of the cruise control module is to monitor and act upon input signals from the cruise control on/off switch (CRUISE CTRL), the cruise control mode switch (RESUME/ACCEL, COAST/SET & CANCEL) and the Vehicle Speed Sensor (VSS) (speedometer).

There are four different categories of input signals received by the cruise control module. These four categories are on/off, speed control, throttle position and cancel.

The on/off input signal to the cruise control module is provided by the cruise control on/off switch (CRUISE CTRL) and simply activates and deactivates the cruise control system.

The speed control input signals to the cruise control module are provided by the cruise control mode switch (RESUME/ACCEL, COAST/SET & CANCEL) and the VSS.

Speed control input signals provided by the cruise control mode switch are the RESUME/ ACCEL (resume/accelerate) signal and the COAST/SET signal. The cruise control module uses these signals, in addition to the vehicle speed signal from the VSS, to determine and maintain or alter vehicle speed in accordance with the driver's commands. The throttle position signals to the cruise control module are provided by the powertrain Control Module (PCM) by means of a Throttle Position (TP) sensor. These signals, as their names suggest, allow the cruise control module to constantly monitor throttle position during cruise control system operation.

The cancel input signals to the cruise control module are provided by the cruise control switch CANCEL button, the stoplamp switch, the transmission range switch (automatic transmission), or the Clutch Pedal Position (CPP) switch (manual transmission). These input signals inform the cruise control module that cruise control operation should be immediately suspended.

Output signals from the cruise control module are all sent to the cruise control actuator and will vary depending upon the type of input signals received.

If, for example, the cruise control module senses that vehicle speed has dropped below the desired cruise speed, an output signal will be sent to the "OPEN" side of the DC servo motor within the cruise control actuator. This action will cause the motor to turn the worm gear, open the throttle, and increase vehicle speed until the desired cruise speed is achieved.

If the cruise control module should sense that vehicle speed is above the desired cruise speed, an output signal is sent to the "CLOSE" side of the DC servo motor within the cruise control actuator. This action will cause the motor to turn in the opposite direction, close the throttle, and decrease vehicle speed until the desired cruise speed is achieved.

Finally, should a cancel input signal be received, the cruise control module de-energizes the magnetic clutch within the actuator. This action disengages the DC servo motor from the worm gear, causing the throttle to go to the idle position and effectively cancelling cruise control operation.