Cruise control is a speed control system that maintains a desired vehicle speed under normal driving conditions. However, steep grades may cause variations in the selected speeds. The electronic cruise control system has the capability to CRUISE, COAST, RESUME SPEED, ACCELERATE, TAP-UP, and TAP-DOWN.
Another feature, internal to the cruise control module is its lash learn feature. The cruise control module has the ability to learn and electronically compensate for up to 4mm of lash in the non-adjustable cruise control cable. The cruise control module maintains this adjustment and updates this information every 30 seconds.
The main parts of the electronic cruise control system are:
| • | The cruise control module assembly |
| • | The function control switches |
| • | The TCC/Brake switch |
| • | The stop lamp switch assembly |
| • | The vehicle speed sensor |
The cruise control system uses the cruise control module assembly to maintain the desired vehicle cruise speed and operation. The cruise control module assembly has a controller and an electric stepper motor to vary the throttle in each different cruise control mode. The controller monitors vehicle speed and operates the stepper motor. The stepper motor operates in response to the controller, to maintain the desired cruise speed. The electric stepper motor moves a strap that is attached to the cruise control cable which moves the throttle linkage. The cruise control module assembly contains a low speed limit which will prevent system engagement below a minimum speed of 40 km/h (25 mph). The module assembly is serviced as an assembly.
The operation of the controller is controlled by the function control switches located on the multifunction turn signal lever. The cruise control functional control switches include the ON/OFF, SET/COAST, resume/accelerate R/A. The switches provide driver control of the cruise control system.
The TCC/Brake and stoplamp switches are used to disengage the cruise control. The TCC/Brake switch assembly and a stoplamp switch assembly are mounted on the brake pedal bracket . To disengage the system the driver presses the brake pedal. The speed of the vehicle at brake actuation will be stored in the memory of the cruise module.
With cruise control, you can maintain a speed of about 40 km/h (25 mph) or more without keeping your foot on the accelerator. When the driver turns off the on/off switch or ignition switch, the cruise control turns off. The vehicle speed stored in the memory of the cruise module will be lost.
Ignition positive voltage is supplied from the cruise control fuse, to the cruise control module. The cruise control module is grounded to the chassis. Ignition positive voltage is supplied from the RLY Ign1 fuse to the cruise control switch and TCC/Brake switch. When the cruise control ON/OFF switch is on, ignition positive voltage is applied to the cruise control on switch signal circuit of the cruise control module. If the driver has not pressed the brake pedal , ignition positive voltage is supplied through the TCC/Brake switch to the cruise release signal circuit of the cruise control module. When the driver presses the brake pedal, battery positive voltage is supplied from the stoplamp fuse, through the closed stoplamp switch contacts, to the stoplamp switch signal circuit of the cruise control module. When the SET/COAST button is pressed , ignition positive voltage is applied to the cruise control set/coast switch signal circuit of the cruise control module. When pressing the resume/accelerate R/A , ignition positive voltage is applied to the cruise control resume/ accelerate switch signal circuit of the cruise control module.
The cruise control module receives a vehicle speed signal from the Powertrain Control Module (PCM). In operation, the voltage varies between 0 V and 5 V.
The cruise control module, cruise engaged circuit, sends a signal to the PCM when cruise is engaged. The cruise control module, cruise inhibit signal circuit, is a circuit used by the PCM to disengage cruise control when conditions inconsistent with cruise operation are present.
After the cruise control engaged criteria has been met, and the cruise control ON and Set/Coast have been commanded, the cruise control module sends a signal to the PCM that the cruise control is engaged. The PCM then sends a class 2 message to the instrument panel cluster (IPC) to illuminate the cruise light, if equipped.
The PCM will inhibit cruise control:
| • | When vehicle speed is less than 40 km/h (25 mph). |
| • | When PARK, REVERSE, NEUTRAL, or 1st gear is indicated. |
| • | With low engine RPM |
| • | With high engine RPM (fuel cut-off) |
| • | When vehicle speed is to high |
| • | When an over or under charged battery voltage condition exists |
| • | Antilock brake system/traction control system is active for more than 2 seconds |
| • | A 6 MPH or more decrease in non-drive wheel speed in 0.4 seconds with out seeing the extended brake travel contacts of the TCC/Brake switch transition. |
If the PCM determines that any of the cruise control inhibit conditions are present, the PCM will disengage the cruise control . The PCM accomplishes this by opening the cruise control inhibit signal circuit.
