GM Service Manual Online
For 1990-2009 cars only

System Description

Caution: Do not use the cruise control on slippery roads, steeply graded roads, or in heavy traffic of heavy or varying volume. Failure to follow these CAUTIONS could possibly cause you to loose control of the vehicle and result in damage to the vehicle and personal injury.

Cruise control is a speed control system that maintains a desired vehicle speed under normal driving conditions. However, steep grades up or down may cause variations in the selected speeds. The cruise control system has the capability to perform the following actions:

    • SET CRUISE SPEED
    • CRUISE
    • COAST
    • RESUME SPEED
    • ACCELERATE
    • TAP UP
    • TAP DOWN

The cruise control circuit contains the following components:

    • A Cruise Control Servo
    • A Cruise Control Module
    • A Cruise Control Switch
    • The Vehicle Speed Sensor (VSS)

The cruise control module and the servo are the two main components that allow the system to control and maintain the desired vehicle speed. The cruise control module monitors vehicle speed and provides the cruise control servo with the necessary commands to maintain or change vehicle speed in response to inputs from the cruise control switch. In response to the control module, the servo moves a connecting arm. The connecting arm is attached to the cruise control cable. The cable moves the throttle linkage in order to vary the throttle position. This action maintains the desired cruise speed. The cruise control module contains a low speed limit that will prevent system engagement below a minimum speed of approximately 40.23 km/h (25 mph). The module is controlled by the cruise control switch. The cruise control is in "Standby Disabled" until all of the conditions that are inconsistent with the cruise control operation are cleared.

Cruise control operation is disengaged when the cruise control module receives a cancel signal from the following components:

    • The Stop Lamp Switch
    • The Cruise Control Switch
    • The Park/Neutral Position (PNP) Switch on vehicles equipped with an auto transaxle
    • The Cruise Control Release Switch on vehicles equipped with an manual transaxle

Upon receiving a cancel signal, the cruise control de-energizes the magnetic clutch inside the cruise control servo. With the magnetic clutch de-energized, the servo and the connecting arm are no longer mechanically connected and the throttle returns to the idle position.

Servo Description


Object Number: 844775  Size: SH

The servo (1) is behind the air cleaner and is mounted to the left strut tower and lower frame rail, the servo consists of a DC servo motor, a worm gear, a throttle angle sensor (potentiometer) and a magnetic clutch. Acting in response to signals from the cruise control module, the servo's DC servo motor actuates the accelerator cable to increase and decrease throttle angle.

Cruise Control Module Description

The cruise control module is located behind the instrument panel cluster. The main function of the cruise control module is to monitor and act upon input signals from the cruise control switch and the Vehicle Speed Sensor (VSS).


Object Number: 844799  Size: SH

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 switch and simply activates and de-activates the cruise control system. The speed control input signals to the cruise module are provided by the cruise control switch and the VSS. Speed control input signals are provided by the cruise control switch are the RES/ACC (Resume/Accelerate) signal and the SET/COAST signal. These signals are also used to initiate the tap-up and tap-down functions. 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 servo and the idle switch inside the 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 signal, the stop lamp switch, the PNP switch, or the cruise control release switch. 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 servo 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 servo. This action will cause the motor to turn the worm gear, open the throttle, and increase vehicle speed until the desired cruise speed is activated. 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 servo. 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 servo. This action disengages the DC servo motor from the worm gear, causing the throttle to go to the idle position and effectively canceling cruise control operation.

The cruise control module also has a self-diagnostic capability. In conjunction with the cruise control switch, it can be used to run an abbreviated self-test which covers all cruise control switch positions, the stoplamp switch, the PNP switch, the cruise control release switch, and the VSS. In addition to the abbreviated self-test, installing a scan tool and selecting Body, then Cruise and placing the module into diagnostic mode will flash DTC codes. The DTC flash codes are displayed by the CRUISE indicator in the instrument cluster. By reading the flash codes and following the diagnostic tables, any electrical problem in the cruise control system can be identified and repaired.

RES/ACC Switch


Object Number: 239402  Size: SH

The RES/ACC (Resume/Accelerate) switch returns cruise control system operation to the last speed setting after a cancel input signal is received by the cruise control module (such as vehicle braking). This switch is activated when the cruise control switch is momentarily moved upward. Do not hold the cruise control switch in this position. Release it immediately. If the cruise control switch is held in the RES/ACC position for more than one second, the system goes into the accelerate mode. If acceleration during cruise control system operation is desired, move the cruise control switch upward into the RES/ACC position and hold it there until the vehicle reaches the desired speed. When the cruise control switch is released, the cruise control system will maintain the new cruise speed. In order to use the accelerate mode, the cruise on-off switch button must have been pressed, the CRUISE indicator must be lit, and the vehicle speed must be over 40 km/h (25 mph).

SET/COAST Switch


Object Number: 239402  Size: SH

The SET/COAST switch is activated when the cruise control switch is moved downward into the SET/COAST position. When the cruise control switch is moved downward into the SET/COAST position and released, the cruise speed will be set at the speed at which the vehicle was traveling when the switch was activated. In order for this switch to operate, however, the cruise on-off switch button must have been pressed, the CRUISE indicator must be lit, and the vehicle speed must be over 40 km/h (25 mph).

The SET/COAST switch can also be used to decrease the cruise speed. By moving the cruise control switch downward into the SET/COAST position and holding it there, the cruise control system will disengage and allow the throttle to return to the idle position. When the new, lower cruise speed has been reached, the cruise control switch is released from the SET/COAST position. Once released, the cruise control system will re-engage and maintain the new desired cruise speed.

The SET/COAST switch can also be used to tap-down vehicle speed. In order to do this, the cruise control system must be engaged and operating. Tapping-down is performed by quickly moving the cruise control switch down into the SET/COAST position and releasing it (or tapping the switch into the SET/COAST position). Do not hold the cruise control switch in the SET/Coast position, or the cruise control system will enter the coast mode. Tap-down is a function in which cruise speed can be decreased by 1.6 km/h (1 mph) increments (one tap = 1.6 km/h [1 mph] decrease).

The accelerator may be pressed at any time to override cruise control system operation. Release of the accelerator will return the vehicle to the previously set cruise speed.

Vehicle Speed Sensor Description

The VSS is an electronic relay that is mounted on the transaxle. As the transaxle turns the VSS, the VSS provides the speedometer with a vehicle speed input (voltage pulses). This input is used to drive the speedometer. The speedometer then converts the Vehicle speed input into a more precise waveform and provides the Powertrain Control Module (PCM) and the cruise control module with its own vehicle speed input. The cruise control module converts this input into a vehicle speed. For vehicle speed sensor replacement procedures, refer to Vehicle Speed Sensor Replacement in Automatic Transmission - MU4, Vehicle Speed Sensor Replacement in Automatic Transmission - MU5, Vehicle Speed Sensor Replacement in Manual Transmission - MK5, or Vehicle Speed Sensor Replacement in Manual Transmission - MTN.

The RES/ACC switch can also be used to tap-up vehicle speed. In order to do this, the cruise control system must be engaged and operating. Tapping-up is performed by quickly moving the cruise control switch up into the RES/ACC position and releasing it (or tapping the switch into the RES/ACC position). Do not hold the cruise control switch in the RES/ACC position, or the cruise control system will enter the accelerate mode. Tap-up is a function in which cruise speed can be increased by 1.6 km/h (1 mph) increments (one tap = 1.6 km/h [1 mph] increase).

Stop Lamp Switch Description

The stop lamp switch is located under the instrument panel directly above the brake pedal. Whenever the brake pedal is pressed, one set of stop lamp switch contacts close and a voltage signal is provided to the cruise control module. The cruise control module disengages cruise control system operation as soon as this voltage signal is sensed.

When the brake pedal is pressed, another set of stop lamp switch contacts open, and the voltage circuit from the cruise control module to the magnetic clutch inside the servo is interrupted. With voltage removed from the magnetic clutch, the servos DC servo motor is disengaged from the worm gear and the throttle is permitted to return to the idle position. This feature is provided to ensure the cancellation of cruise control system operation during vehicle braking. For stop lamp switch replacement and adjustment procedures, refer to Stop Lamp Switch Replacement in Lighting Systems.

Clutch Control Release Switch Description

The cruise control release switch is mounted under the instrument panel directly above the clutch pedal. Whenever the clutch pedal is pressed, the cruise control release switch closes and provides a ground to the cruise control module. The cruise control module disengages cruise control system operation as soon as this ground signal is sensed.

Park/Neutral Position (PNP) Switch Description


Object Number: 239411  Size: SH

The PNP switch (2) is mounted to the transaxle. Whenever the manual selector lever is placed in either the Park (P) or Neutral (N) position, the PNP switch closes and provides a ground to the cruise control module. The cruise control module disengages cruise control system operation as soon as this ground signal is sensed. For PNP switch replacement and adjustment procedures, refer to Park/Neutral Position Switch in Automatic Transaxle - MU4, or Park/Neutral Position Switch in Automatic Transaxle - MU5.

Cruise On-Off Switch


Object Number: 239402  Size: SH

The cruise on-off switch is a momentary contact type button located on the end of the cruise control switch. The purpose of the cruise on-off switch is to turn the cruise control system ON and OFF.

Cruise Indicator Description

The CRUISE indicator, located in the instrument cluster assembly, turns ON to inform the driver that the cruise control system is operational. The CRUISE indicator is also used during cruise control system diagnosis.

System Operation

To Set Cruise Control

    Caution: Do not use the cruise control on slippery roads, steeply graded roads, or in heavy traffic of heavy or varying volume. Failure to follow these CAUTIONS could possibly cause you to loose control of the vehicle and result in damage to the vehicle and personal injury.

  1. Drive the vehicle above 40 km/h (25 mph).
  2. Depress and release the CRUISE ON OFF button.
  3. Accelerate to the desired speed.
  4. Move the cruise control switch downward to the SET/COAST position and release.
  5. Take your foot off the accelerator pedal.

To Resume a Set Speed

Suppose you set your cruise control at a desired speed and then you apply the brake. This, of course, shuts off the cruise control. But you do not need to reset it. Once you are going 40 km/h (25 mph) or more, you can move the cruise control switch upward to the RES/ACC position and release. You will go right back up to your chosen speed and stay there. If the vehicle speed drops below 40 km/h (25 mph) or you turn the ignition off or turn the cruise switch off, you will erase memory.

To Get Out of Cruise Control

There are 3 ways to turn off the cruise control.

    • Step lightly on the brake pedal.
    • Depress and release the CRUISE ON OFF button.
    • Depress the clutch pedal -manual transmissions.

Passing Another Vehicle While Using Cruise Control

Use the accelerator pedal to increase your speed. When you take your foot off the pedal, the vehicle will slow down to the cruise control speed you set earlier.

To Increase Speed While Using Cruise Control

There are two ways to gain higher speed while using cruise control.

    • Use the accelerator pedal to get to the higher speed, move the cruise control switch downward to the SET/COAST position and release. You will now cruise at the higher speed.
    • Move the cruise switch upward to the RES/ACC position, hold it there until you get up to the speed you want and release. To increase your speed in very small amounts, move the cruise control switch upward to the RES/ACC position for less than 3/4 of a second and release it. Each time you do this, your vehicle will go approximately 1.6 km/h (1 mph) faster.

The accelerate feature will only work after you turn on the cruise control by pushing and releasing the ON OFF button and setting a cruise control speed.

Using Cruise Control on Hills

How well your cruise control will work on hills depends upon your speed, load, and the incline of the hills. When going up steep hills, you may have to step on the accelerator pedal to maintain your speed. When going downhill, you may have to brake or shift to a lower gear to keep your speed down. Of course, applying the brake takes you out of cruise control. Many drivers find this to be too much trouble and do not use cruise control on steep hills.

To Erase Cruise Speed Memory

When you turn off the cruise control switch or the ignition is turned off or the vehicle speed drops below 40 km/h (25 mph), the cruise control set speed memory is erased.

To Reduce Speed While Using Cruise Control

There are 2 ways to reduce your speed while using cruise control.

    • Move the cruise control switch downward to the SET/COAST position and hold until you obtain the lower speed you want. Then release it.
    • To slow down in very small amounts move the cruise control switch downward to the SET/COAST for less than 3/4 of a second and release. Each time you do this, you will go approximately 1.6 km/h (1 mph) slower.

Circuit Operation

Battery voltage is applied to terminal 2 of the cruise control module when the ignition switch is in the ON position. When the cruise control switch is pressed to the CRUISE ON OFF position, ground is applied to the internal switch of the cruise control module at terminal 11.

The cruise control switch signals the cruise control module (CCM) at terminal 11 to enter the CANCEL, SET/COAST, or RES/ACC by using varying amounts of resistance depending on the mode selected.

Ground is supplied to the CCM at terminal 16 from G200.

Outputs from the CCM are found on the following terminals:

    •  5 -- cruise control indicator -completes the circuit to light the cruise control indicator
    •  7 -- servo motor
    •  8 -- magnetic clutch -for the servo motor
    •  10 -- DLC
    • 14 -- O/D cut control -informs the PCM to downshift from overdrive
    • 15 -- servo motor

Inputs to the CCM are found on the following terminals:

    •  2 -- Ignition Positive Voltage
    •  4 -- cruise interrupt signal -transaxle range switch not in DRIVE (D) or clutch pedal pressed
    •  6 -- shift solenoid 2 control -informs the CCM when the transaxle is in 2nd or 3rd gear and is out of overdrive mode
    •  8 -- brake signal -disables cruise when the brake pedal is pressed
    • 11 -- cruise control switch -mode switch
    • 12 -- vehicle speed -from the PCM
    • 13 -- idle signal control -informs the ccm when the accelerator is pressed and engine is above idle
    • 16 -- ground

Cruise control will be disabled when one or more of the following conditions exist:

    • The VSS is less than 40 km/h (25 mph).
    • The transaxle range switch indicates that the vehicles is not in DRIVE (D).
    • The clutch pedal is depressed -manual transaxle.
    • There is an over/under battery voltage condition.
    • The brake pedal is pressed
    • The engine RPMs are low -idle.