The speed control system consists of the following components
- Speed control switches
- Speed control deactivator switch (part of the stoplamp switch)
- Stoplamp switch
- Speed control indicator
- Clutch pedal speed control deactivator switch (manual transaxle)
- PCM
- Electronically-controlled throttle body
- Clockspring
The speed control system is controlled by the PCM. The speed control system is designed to maintain a selected vehicle speed between 48 km/h (30 mph) and the maximum limited vehicle speed. The speed control system is controlled by the steering wheel mounted switches (ON, OFF, SET+, SET-, and RESUME), clutch pedal speed control deactivator switch (manual transaxle), and the brake pedal. The steering wheel mounted switches are hardwired to the PCM.
It is normal for the engine RPM to increase slightly and then drop off slowly when the clutch pedal is applied during operation.
The speed control functions include
- turning the speed control system on.
- setting and maintaining the desired vehicle speed.
- accelerating the vehicle speed.
- decelerating the vehicle speed.
- resuming the prior vehicle speed.
- turning the vehicle speed control system off.
- canceling the speed control.
Principles of Operation
Note. The Smart Junction Box (SJB) is also known as the Generic Electronic Module (GEM).
The speed control system is controlled by the PCM. The speed control system is designed to maintain a selected vehicle speed between 40 km/h (25 mph) and the maximum limited vehicle speed. The speed control system is controlled by the steering wheel mounted switches (ON, OFF, SET+, SET-, and RESUME), the stoplamp switch, the clutch pedal speed control deactivator switch (manual transaxle), and the speed control deactivator switch. The steering wheel mounted switches are hardwired to the PCM through the clockspring.
The speed control functions include
- turning the speed control system on.
- setting and maintaining the desired vehicle speed.
- accelerating the vehicle speed.
- decelerating the vehicle speed.
- turning the vehicle speed control system off.
- cancelling the speed control.
Pressing and releasing the ON switch turns the speed control system on. Pressing and releasing the SET+ or SET- switch while the vehicle is traveling at the desired speed activates the speed control system.
Tapping the SET+ or the SET- switch while in the set mode increases or decreases the maintained vehicle speed by 1.6 km/h (1 mph) per tap, respectively. If either switch is pressed and held, the vehicle speed continues to accelerate (SET+) or decelerate (SET-) until the switch is released.
Pressing and releasing the OFF switch, or switching the ignition switch to the OFF position, turns the speed control system off. Applying the brake pedal or clutch pedal (manual transaxle) puts the speed control system into the standby mode. Pressing the RESUME switch when the speed control system is in the standby mode causes the vehicle to accelerate to the last set speed. The RESUME switch does not function if the OFF switch is pressed or if the current vehicle speed is below the minimum operational speed.
Whenever the speed control system is engaged and active, a speed control icon on the Instrument Cluster (IC) is illuminated.
The clutch pedal speed control deactivator switch is used on vehicles equipped with a manual transaxle. When the clutch pedal is applied with the vehicle speed control system engaged, the normally closed switch opens and signals the PCM to deactivate the speed control.
When the brake pedal is applied, an electrical signal from the stoplamp switch is sent to the PCM to deactivate the speed control system. The speed control deactivator switch is provided as an additional safety feature. Under increased brake pedal effort, the speed control deactivator switch opens and removes the voltage signal from the PCM input circuit, deactivating the speed control system.
The clockspring provides the electrical interface between the steering column wiring and the speed control switches in the steering wheel.
The inputs to the PCM are
- Output Shaft Speed (OSS) sensor (Except hybrid)
- Transmission Range (TR) sensor
- Speed control switch(es)
- Clutch pedal speed control deactivator switch (manual transaxle)
- Stoplamp switch
- Speed control deactivator switch
- Accelerator pedal position sensor
The outputs of the PCM for the speed control system are
- Speed control indicator lamp
- Throttle command
The speed control system throttle position is completely controlled by the PCM through the electronically controlled throttle body. Speed control electronics are contained entirely within the PCM.
For all vehicles except hybrid, when the speed control system is active, the PCM corrects for deviations in the actual vehicle speed by proportionally moving the throttle plate. The PCM modulates the throttle to minimize error between actual and desired vehicle speed. The PCM strategy uses the throttle control for smooth accelerations.
For hybrid vehicles, when the electric traction motor is powering the vehicle and the speed control is active, the electronic actuator corrects for deviations in the actual vehicle speed by proportionally applying wheel torque. The control electronics modulate the wheel torque to minimize error between the actual vehicle speed and the desired speed.
The PCM sends a message over the High Speed Controller Area Network (HS-CAN) to the IC whenever the speed control telltale should be turned on or off.
For all vehicles except hybrid, in the event of an OFF command or a deactivation request from any source, the speed control system carries out a deactivation and immediately returns the throttle to the idle position.
For hybrid vehicles, in the event of an off command or a deactivation request from any source except a brake pedal tap, the system carries out a hard deactivation and immediately returns control to the accelerator pedal.
The ABS module monitors brake pressure and also receives the stoplamp switch input from the SJB along the HS-CAN bus. A fault in the ABS module can disable the speed control system.
The speed control system provides self-diagnostics. The speed control is disabled anytime an error is detected in the system. No IC telltale or message center messages are displayed when faults occur. Fault codes are logged by the PCM.
An electronically controlled throttle system fault also causes the speed control system to be disabled and a warning telltale (wrench light) or a message center message is displayed.
Additionally, the following conditions cause the speed control system to deactivate
- Transmission gear selector in a position other than D or OD (automatic transaxle)
- Vehicle clutch pedal is applied (manual transaxle)
- Speed control set speed is over-ridden with the accelerator pedal for a period longer than 5 minutes
- Vehicle speed loss from set speed of greater than 16 km/h (10 mph) occurs
- Vehicle speed falls below the minimum allowable limit of 40 km/h (25 mph)
- Parking brake is applied
- Speed control switch is pressed or stuck for longer than 2 minutes
- Traction control event
- ABS system fault
Normal Operation
The PCM sends a signal through circuit VES10 (WH) to the speed control switches, which passes through the clockspring. The return signal is sent to the PCM through circuit RES08 (GN/BN) and the clockspring. When the brake pedal is applied, the stoplamp switch sends a voltage signal to the PCM on circuit CCB08 (VT/WH) to deactivate the speed control if engaged.
The speed control deactivator switch (part of the stoplamp switch) interrupts circuit CES09 (VT/OG) removing the voltage signal to the PCM when the brake pedal is applied. This is a redundant signal to the PCM.
Vehicles equipped with a manual transaxle have an additional clutch pedal speed control deactivator switch. The clutch pedal speed control deactivator switch, normally closed, supplies a ground signal to the PCM through circuit CET21 (GN/WH). When the clutch pedal is pressed, the clutch pedal speed control deactivator switch moves to the open position, removing the ground signal from the PCM, which deactivates the speed control. Circuit GD120 (BK/GN) supplies ground to the clutch pedal speed control deactivator switch.
The ABS module monitors brake pressure and also receives the stoplamp switch input from the Smart Junction Box (SJB) along the High Speed Controller Area Network (HS-CAN) bus. A fault in the ABS module can disable the speed control system.
This pinpoint test is intended to diagnose the following
- Wiring, terminals or connectors
- PCM not configured for speed control
- Stoplamp switch
- Clutch Pedal Position (CPP) switch
- Speed control switch
- Digital Transmission Range (TR) sensor
- Vehicle speed signal
- PCM
- ABS module
- Park brake
When the brake pedal is applied, the stoplamp switch closes and sends voltage to the PCM on circuit CCB08 (VT/WH) to deactivate the speed control, if engaged.
The speed control deactivator switch (part of the stoplamp switch) receives voltage on circuit CBK02 (GN) and interrupts circuit CES09 (VT/OG) removing the voltage signal to the PCM when the brake pedal is applied firmly and passes the speed control deactivator switch point. This is a redundant signal to the PCM.
The ABS module monitors brake pressure and also receives the stoplamp switch input from the Smart Junction Box (SJB) along the High Speed Controller Area Network (HS-CAN) bus. A fault in the ABS module can disable the speed control system.
- DTC P1572 (Brake Switch Circuit) - sets when the PCM does not sense the proper sequence of the brake pedal input signal from both the stoplamp and deactivator switches when the brake pedal is pressed and released.
- DTC P1703 (Brake Switch Out Of Self Test Range) - sets when there is an open or short in the deactivator switch circuits or when there is an open or short in the stoplamp circuits.
This pinpoint test is intended to diagnose the following
- Wiring, terminals or connectors
- Speed control deactivator switch (integral to the stoplamp switch)
- PCM
The PCM sends a signal through circuit VES10 (WH) to the speed control switches, which passes through the clockspring. The return signal is sent to the PCM through circuit RES08 (GN/BN) and the clockspring.
- DTC P0579 (Cruise Control Multifunction Input A Circuit Range/Performance) - sets when the speed control switch circuits are open, shorted to voltage or ground.
- DTC P0581 (Cruise Control Multi-Function Input A Circuit High) - sets when the speed control switch circuits are open or shorted to voltage.
This pinpoint test is intended to diagnose the following
- Wiring, terminals or connectors
- Clockspring
- Speed control switches
- PCM
Vehicles equipped with a manual transaxle have an additional clutch pedal speed control deactivator switch. The clutch pedal speed control deactivator switch, normally closed, supplies a ground signal to the PCM through circuit CET21 (GN/WH). When the clutch pedal is pressed, the clutch pedal speed control deactivator switch moves to the open position, removing the ground signal from the PCM, which deactivates the speed control. Circuit GD120 (BK/GN) supplies ground to the clutch pedal speed control deactivator switch.
This pinpoint test is intended to diagnose the following
- Wiring, terminals or connectors
- Clutch pedal speed control deactivator switch
- PCM