SECTION 9U
CRUISE CONTROL SYSTEM
Caution : Disconnect the negative battery cable before removing or installing any electrical unit or when a tool or equipment could easily come in contact with exposed electrical terminals. Disconnecting this cable will help prevent personal injury and damage to the vehicle. The ignition must also be in LOCK unless otherwise noted.
SPECIFICATIONS
Fastener Tightening Specifications
Application | N•m | Lb-Ft | Lb-In |
Cruise Control Switch Screw | 2.5 | - | 22 |
SCHEMATIC AND ROUTING DIAGRAM
Cruise Control System
DIAGNOSIS
Cruise Control Diagnosis
Cruise Control Does Not Operate
| Step | Action | Value(s) | Yes | No |
| 1 | Check fuses F13. Is fuse blown? | - | Go to Step 2 | Go to Step 3 |
| 2 | - Check for a short circuit and repair it, if necessary.
- Replace the blown fuse.
Is the repair complete? | - | System OK | - |
| 3 | - Turn the ignition ON.
- Check the voltage at fuses F13.
Is the voltage equal to the specified value? | 11-14 v | Go to Step 5 | Go to Step 4 |
| 4 | Repair the power supply to the fuse. Is the repair complete? | - | System OK | - |
| 5 | - Turn the ignition ON.
- Turn the cruise control switch OFF.
- Use a voltmeter to check the voltage at terminal 17 of the J5 BCM connector.
Is the resistance equal to the specified value? | ≈ 0 Ω | Go to Step 7 | Go to Step 6 |
| 6 | Repair the short to voltage between the cruise control on switch and the J5 BCM connector terminal 17. Is the repair complete? | - | System OK | - |
| 7 | - Turn the ignition ON.
- Turn the cruise control switch ON.
- Use a voltmeter to check the voltage at terminal 17 of the J5 BCM connector.
Is the voltage equal to the specified value? | 11-14 v | Go to Step 9 | Go to Step 8 |
| 8 | Repair the open circuit between fuse F13 and the terminal 17 of the J5 BCM connector. Is the repair complete? | - | System OK | - |
| 9 | - Turn the ignition ON.
- Turn the cruise control switch ON.
- Check the voltage at terminals 3 and 7 of the J5 BCM connector.
Is the resistance equal to the specified value? | ≈ 0 Ω | System OK | Go to Step 10 |
| 10 | Replace the cruise control switch. Is the repair complete? | - | System OK | - |
MAINTENANCE AND REPAIR
ON-VEHICLE SERVICE
Cruise Control Switch
Removal Procedure
- Remove the SIR module. Refer to Section 8B, Supplemental Inflatable Restraints (SIR).
- Remove the steering wheel side cover.
- Remove the cruise control switch.
Installation Procedure
- Install the cruise control switch.
- Install the steering wheel side cover.
Tighten
Tighten the cruise control switch screws to 2.5 N•m (22 lb-in).
- Install the SIR module. Refer to Section 8B, Supplemental Inflatable Restraints (SIR).
GENERAL DESCRIPTION AND SYSTEM OPERATION
Cruise Control Description and Operation
Cruise control is a speed control system that maintains a desired vehicle speed under normal driving conditions at vehicle speeds above 40 km/h (24.9 mph). Steep grades may cause variations in the selected vehicle speeds.
The following are the main components of the Cruise Control System:
- The accelerator pedal
- The brake pedal switch
- The clutch pedal position switch, if equipped with a manual transmission
- The cruise control cancel switch
- The body control module (BCM)
- The On/Off switch
- The engine control module (ECM)
- The ACCEL/RES switch
- The SET/COAST switch
- The throttle actuator control (TAC) motor
- The vehicle speed sensor (VSS)
The body control module (BCM) monitors the signal circuit of the cruise control switches, which are located on the steering wheel. The BCM relays the cruise control switch status to the engine control module (ECM) via the GMLAN serial data circuit. The ECM uses the status of the cruise control switch to determine when to capture and maintain the vehicle speed. The ECM monitors the vehicle speed signal circuit in order to determine the desired vehicle speed. The ECM uses the TAC motor in order to maintain the vehicle speed. For further information of the TAC System, refer to
"Throttle Actuator Control (TAC) System Description" in 1F, Engine Controls.Voltage is supplied to the cruise control switch via the steering wheel control switch reference voltage circuit supplied by the BCM. The cruise control function switches are arranged in a resistive ladder design, with each cruise control function switch having a different resistance value. The BCM detects a specific voltage value that is associated with the cruise control function switch being activated. When the normally open cruise control on/off switch is turned ON, the switch closes and the BCM sends a GMLAN serial data message to the ECM indicating that the on/off switch is active. Similarly, when the normally open ACCEL/RES switch or the normally open SET/COAST switch are pressed, the switch closes and the BCM detects the predetermined voltage signal on the cruise control resume/accel and set/coast switch signal circuit. The BCM sends a GMLAN serial data message to the ECM indicating that the ACCEL/RES switch or the SET/COAST switch is active. The ACCEL/RES switch or the SET/COAST switch will remain inactive when the BCM has not received the predetermined voltage signal from the on/off switch.
Cruise Control Engaged
The Cruise Control System will engage and adjust vehicle speeds, based on the activation of the following cruise control switches:
To engage the Cruise Control System, ensure that the vehicle speed is above 40 km/h (24.9 mph), turn the cruise On/Off switch ON and momentarily press the SET/COAST switch. The ECM will engage the Cruise Control System and record the vehicle speed. The ECM sends a GMLAN serial data message to the instrument panel cluster (IPC) in order to illuminate the Cruise Engaged indicator in the IPC.
Pressing the accelerator pedal while the Cruise Control System is engaged, allows the driver to override the Cruise Control System in order to accelerate the vehicle beyond the current set vehicle speed. When the accelerator pedal is released, the vehicle will decelerate and resume the current set vehicle speed. The driver can also override the current set vehicle speed via the SET/COAST switch and the ACCEL/RES switch. When the Cruise Control System is engaged, pressing and holding the SET/COAST switch will allow the vehicle to decelerate from the current set vehicle speed without deactivating the Cruise Control System. When the SET/COAST switch is released, the ECM will record the vehicle speed and maintain the vehicle speed as the new set vehicle speed. When the Cruise Control System is engaged, momentarily pressing the SET/COAST switch will allow the vehicle to decelerate at 2 km/h (1.2 mph) increments for each time that the SET/COAST is momentarily pressed, with a minimum vehicle speed of 38 km/h (23.6 mph).
Pressing and holding the ACCEL/RES switch, when the Cruise Control System is engaged, will allow the vehicle to accelerate to a greater vehicle speed than the current set vehicle speed. When the ACCEL/RES switch is released, the ECM will record the vehicle speed and maintain the vehicle speed as the new set vehicle speed. When the Cruise Control System is engaged, momentarily pressing the ACCEL/RES switch will allow the vehicle to accelerate at 2 km/h (1.2 mph) increments for each time that the ACCEL/RES switch is momentarily pressed. Momentarily activating the ACCEL/RES switch will recall the previous vehicle speed, after the cruise control system is disengaged by pressing the brake or clutch pedal or by activating the CANCEL switch.
Cruise Control Disengaged
The engine control module (ECM) disengages the cruise control operation based on the signals from the following switches:
- The brake pedal switch
- The clutch pedal position switch, if equipped
- The cruise on/off switch
- The cruise control cancel switch
The Cruise Control System will disengage when the brake pedal is applied. The body control module (BCM) monitors the brake pedal switch via the brake pedal switch signal circuit. The ECM monitors the brake pedal switch signal through a discrete input and a GMLAN serial data message signal from the BCM indicating the brake status. When both signals indicate the brake pedal is applied, the ECM will disengage the cruise control system. When the clutch pedal is applied, the normally closed clutch pedal position switch opens and the ECM detects a low signal voltage on the clutch pedal position switch signal circuit.
The Cruise Control System will also disengage when the cruise control on/off switch is switched OFF, or the cruise control cancel switch is activated. The body control module (BCM) determines when the cruise control cancel switch is activated. When the normally open cancel switch is closed, the BCM detects the predetermined voltage signal on the cruise control function switch circuit. The vehicle speed stored in the memory of the engine control module will be erased when the cruise control On/Off switch is turned OFF, or the ignition switch is turned OFF. The BCM sends a GMLAN serial data message to the ECM in order to disengage the cruise control system. The Cruise Control System will disengage when the ECM detects that a driver override function has been active for approximately 300 seconds (FAMⅡ 2.4D) / 60 seconds (HFV6 3.2L) / 30 seconds (2.0 DSL). When the Cruise Control System has been disengaged, the ECM sends a GMLAN serial message to the instrument panel cluster (IPC) in order to turn OFF the Cruise Engaged indicator.
Cruise Control Inhibited
The engine control module (ECM) inhibits the cruise control operation when any of the following conditions exist:
- The ECM has not detected a brake pedal activation from the body control module (BCM).
- A Cruise Control System related DTC has been set.
- The vehicle speed is less than 40 km/h (24.9 mph).
- The vehicle is in PARK, REVERSE, NEUTRAL, or 1st gear.
- The engine RPM too low.
- The engine RPM is too high.
- The vehicle speed is too high.
- The system voltage is not between 6-16 volts.
- The Antilock Brake System (ABS)/Traction Control System (TCS) is active for more than 2 seconds.
