Cruise Control System: Other Chevrolet Silverado 2500 HD

Reference Information

Schematic Reference

1. «Cruise Control Schematics»(ref-278059-S22088995062008012100000)
2. «Body Control System Schematics»(ref-278002-S22677490482008012100000)

Connector End View Reference

1. «Secondary/Configurable Control Connector End Views»(ref-278061-S22500883172008012100000)
2. «Data Communication Connector End Views»(ref-278002-S06109933032008012100000)

Description and Operation

Cruise Control Description and Operation

Electrical Information Reference

1. «Circuit Testing»(ref-278019-S01379251932008012100000)
2. «Connector Repairs»(ref-278019-S06982211772008012100000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-278019-S21810776732008012100000)
4. «Wiring Repairs»(ref-278019-S25320832652008012100000)

Scan Tool Reference

1. «Scan Tool Data List»(ref-278059-S25172490122008012100000)
2. «Scan Tool Data Definitions (Disengage History)»(ref-278059-S11775083392008012100000)

Circuit/System Verification

Ignition ON, observe the scan tool Cruise Control Switch parameter in the BCM while pressing the various cruise control switches. The reading should match accordingly with each depressed switch.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Steering Wheel Control Switch Assembly Replacement»(ref-278061-S38011245532008012100000)
2. «Control Module References»(ref-278020-S09054666032008012100000) for BCM replacement, setup, and programming

Schematic Reference

1. «Cruise Control Schematics»(ref-278059-S22088995062008012100000)
2. «Body Control System Schematics»(ref-278002-S22677490482008012100000)

Connector End View Reference

1. «Secondary/Configurable Control Connector End Views»(ref-278061-S22500883172008012100000)
2. «Data Communication Connector End Views»(ref-278002-S06109933032008012100000)

Description and Operation

Cruise Control Description and Operation

Electrical Information Reference

1. «Circuit Testing»(ref-278019-S01379251932008012100000)
2. «Connector Repairs»(ref-278019-S06982211772008012100000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-278019-S21810776732008012100000)
4. «Wiring Repairs»(ref-278019-S25320832652008012100000)

Scan Tool Reference

1. «Scan Tool Data List»(ref-278059-S25172490122008012100000)
2. «Scan Tool Data Definitions (Disengage History)»(ref-278059-S11775083392008012100000)

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Steering Wheel Control Switch Assembly Replacement»(ref-278061-S38011245532008012100000)
2. «Control Module References»(ref-278020-S09054666032008012100000) for BCM replacement, setup, and programming

Schematic Reference

Exterior Lights Schematics

Connector End View Reference

Lighting Systems Connector End Views

Description and Operation

Cruise Control Description and Operation

Electrical Information Reference

1. «Circuit Testing»(ref-278019-S01379251932008012100000)
2. «Connector Repairs»(ref-278019-S06982211772008012100000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-278019-S21810776732008012100000)
4. «Wiring Repairs»(ref-278019-S25320832652008012100000)

Scan Tool Reference

1. «Scan Tool Data List»(ref-277990-S24476710372008012100000)
2. «Scan Tool Data Definitions»(ref-277990-S11026152172008012100000)

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Stop Lamp Switch Replacement (Non-Adjustable Pedal)»(ref-277990-S11135182422008012100000) or «Stop Lamp Switch Replacement (Adjustable Pedal)»(ref-277990-S15477018612008012100000)
2. «Control Module References»(ref-278020-S09054666032008012100000) for ECM replacement, setup, and programming.

Schematic Reference

Exterior Lights Schematics

Connector End View Reference

Lighting Systems Connector End Views

Description and Operation

Cruise Control Description and Operation

Electrical Information Reference

1. «Circuit Testing»(ref-278019-S01379251932008012100000)
2. «Connector Repairs»(ref-278019-S06982211772008012100000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-278019-S21810776732008012100000)
4. «Wiring Repairs»(ref-278019-S25320832652008012100000)

Scan Tool Reference

1. «Scan Tool Data List»(ref-277990-S24476710372008012100000)
2. «Scan Tool Data Definitions»(ref-277990-S11026152172008012100000)

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Stop Lamp Switch Replacement (Non-Adjustable Pedal) or Stop Lamp Switch Replacement (Adjustable Pedal)

Schematic Reference

Exterior Lights Schematics

Connector End View Reference

Lighting Systems Connector End Views

Description and Operation

Cruise Control Description and Operation

Electrical Information Reference

1. «Circuit Testing»(ref-278019-S01379251932008012100000)
2. «Connector Repairs»(ref-278019-S06982211772008012100000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-278019-S21810776732008012100000)
4. «Wiring Repairs»(ref-278019-S25320832652008012100000)

Scan Tool Reference

1. «Scan Tool Data List»(ref-277990-S24476710372008012100000)
2. «Scan Tool Data Definitions»(ref-277990-S11026152172008012100000)

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Stop Lamp Switch Replacement (Non-Adjustable Pedal) or Stop Lamp Switch Replacement (Adjustable Pedal)

Schematic Reference

1. «Cruise Control Schematics»(ref-278059-S22088995062008012100000)
2. «Body Control System Schematics»(ref-278002-S22677490482008012100000)

Connector End View Reference

1. «Secondary/Configurable Control Connector End Views»(ref-278061-S22500883172008012100000)
2. «Data Communication Connector End Views»(ref-278002-S06109933032008012100000)

Electrical Information Reference

1. «Circuit Testing»(ref-278019-S01379251932008012100000)
2. «Connector Repairs»(ref-278019-S06982211772008012100000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-278019-S21810776732008012100000)
4. «Wiring Repairs»(ref-278019-S25320832652008012100000)

Scan Tool Reference

Scan Tool Data List

Ignition ON, observe the scan tool Cruise Control Switch parameter in the BCM while pressing the cruise control switch ON and OFF. The reading should change between ON and OFF.

1. If the parameter does not switch between ON and OFF, replace the BCM.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for BCM replacement, setup, and programming

Schematic Reference

Cruise Control Schematics

Connector End View Reference

Data Communication Connector End Views

Electrical Information Reference

1. «Circuit Testing»(ref-278019-S01379251932008012100000)
2. «Connector Repairs»(ref-278019-S06982211772008012100000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-278019-S21810776732008012100000)
4. «Wiring Repairs»(ref-278019-S25320832652008012100000)

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for BCM replacement, setup, and programming

Symptoms - Cruise Control

1. Perform the «Diagnostic System Check - Vehicle»(ref-278018-S19353494792008012100000) , before using the Symptom Tables in order to verify that all of the following are true: There are no DTCs set. The control modules can communicate via the serial data link.
2. Review the system operation in order to familiarize yourself with the system functions. Refer to «Cruise Control Description and Operation»(ref-278059-S42389829672008012100000) .

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections .

Schematic Reference

1. «Cruise Control Schematics»(ref-278059-S22088995062008012100000)
2. «Body Control System Schematics»(ref-278002-S22677490482008012100000)

Connector End View Reference

1. «Secondary/Configurable Control Connector End Views»(ref-278061-S22500883172008012100000)
2. «Data Communication Connector End Views»(ref-278002-S06109933032008012100000)

Electrical Information Reference

1. «Circuit Testing»(ref-278019-S01379251932008012100000)
2. «Connector Repairs»(ref-278019-S06982211772008012100000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-278019-S21810776732008012100000)
4. «Wiring Repairs»(ref-278019-S25320832652008012100000)

Scan Tool Reference

Scan Tool Data List

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Steering Wheel Control Switch Assembly Replacement»(ref-278061-S38011245532008012100000)
2. «Control Module References»(ref-278020-S09054666032008012100000) for BCM replacement, setup, and programming.

Conditions for Enabling Cruise Control

1. The vehicle speed is greater than 40 km/h (25 mph).
2. The vehicle is not in PARK, REVERSE, NEUTRAL, or 1st gear.
3. The system voltage is within 9-16 volts.
4. The park brake or brakes is not applied.

Schematic Reference

1. «Cruise Control Schematics»(ref-278059-S22088995062008012100000)
2. «Body Control System Schematics»(ref-278002-S22677490482008012100000)

Connector End View Reference

1. «Secondary/Configurable Control Connector End Views»(ref-278061-S22500883172008012100000)
2. «Data Communication Connector End Views»(ref-278002-S06109933032008012100000)

Description and Operation

Cruise Control Description and Operation

Electrical Information Reference

1. «Circuit Testing»(ref-278019-S01379251932008012100000)
2. «Connector Repairs»(ref-278019-S06982211772008012100000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-278019-S21810776732008012100000)
4. «Wiring Repairs»(ref-278019-S25320832652008012100000)

Scan Tool Reference

1. «Scan Tool Data List»(ref-278059-S25172490122008012100000)
2. «Scan Tool Data Definitions (Disengage History)»(ref-278059-S11775083392008012100000)

Ignition ON, cruise on/off switch ON, rotate the steering wheel to both steering stops while activating each cruise control switch separately. With a scan tool, observe all cruise control switch parameters in the BCM. Verify that each cruise control switch activated and that each displayed switch position parameters match accordingly with each depressed switch, as the steering wheel is turned.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Steering Wheel Control Switch Assembly Replacement»(ref-278061-S38011245532008012100000)
2. «Control Module References»(ref-278020-S09054666032008012100000) for BCM replacement, setup, and programming

Cruise Control Engaged

The Cruise Control System will engage and adjust vehicle speeds, based on the activation of the following cruise control switches, which are located on the steering wheel

1. The on/off switch
2. The + RES switch
3. The - SET switch

The body control module (BCM) monitors the signal circuit of the cruise control switches. 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 throttle actuator control (TAC) motor in order to maintain the vehicle speed. For further information on the TAC System, refer to Throttle Actuator Control (TAC) System Description .

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 supplies a ground to the cruise control switch ON indicator circuit as it becomes illuminated. The BCM sends a GMLAN serial data message to the ECM indicating that the on/off switch is active. Similarly, when the normally open + RES switch or the normally open - SET switch are pressed, the switch closes and the BCM detects the predetermined voltage signal on the cruise control set/coast and resume/accel switch signal circuit. The BCM sends a GMLAN serial data message to the ECM indicating that the + RES switch or the - SET switch is active. To engage the Cruise Control System, ensure that the vehicle speed is above 40.2 km/h (25 mph), turn the cruise On/Off switch ON and momentarily press the - SET switch. The ECM will engage the Cruise Control System and record the vehicle speed. The ECM sends a GMLAN serial data message to the driver information center (DIC) in order to illuminate the CRUISE SET TO ### message. 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. The - SET switch and the + RES switch will remain inactive when the BCM has not received the predetermined voltage signal from the on/off switch. Pressing the accelerator pedal, while the Cruise Control System is engaged, will allow 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 switch and the + RES switch. When the Cruise Control System is engaged, pressing and holding the - SET switch will allow the vehicle to decelerate from the current set vehicle speed without deactivating the Cruise Control System. When the - SET 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 switch will allow the vehicle to decelerate at 1.6 km/h (1 mph) increments for each time that the - SET is momentarily pressed, with a minimum vehicle speed of 37 km/h (23 mph). Pressing and holding the + 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 + 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 + RES switch will allow the vehicle to accelerate at 1.6 km/h (1 mph) increments for each time that the + RES switch is momentarily pressed, with the maximum acceleration total of 16 km/h (10 mph) over the current set vehicle speed. Momentarily activating the + RES switch will recall the previous vehicle speed, after the cruise control system is disengaged by pressing the brake 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

1. The stop lamp switch
2. The cruise control On/Off switch
3. The cruise control cancel switch

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 BCM sends a GMLAN serial data message to the ECM in order to disengage the cruise control system.

The stop lamp switch is mounted on the brake pedal bracket. When the brake pedal is applied, the normally open stop lamp switch closes. The ECM monitors the stop lamp signal circuit 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.

The Cruise Control System will disengage when the cruise control on/off switch is switched OFF. 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 Cruise Control System will disengage when the ECM detects that a driver override function has been active for approximately 60 seconds. 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, and to the driver information center (DIC) in order to turn OFF the CRUISE SET TO ### message.

Cruise Control Inhibited

The engine control module (ECM) inhibits the cruise control operation when any of the following conditions exist

1. The ECM has not detected a brake pedal activation from the body control module (BCM).
2. A Cruise Control System DTC has been set.
3. The vehicle speed is less than 40.2 km/h (25 mph).
4. The vehicle speed is too high.
5. The vehicle is in PARK, REVERSE, NEUTRAL, or 1st gear.
6. The engine RPM is too low.
7. The engine RPM is too high.
8. The system voltage is not between 9-16 volts.
9. The Antilock Brake System (ABS)/Traction Control System (TCS) is active for more than 2 seconds.