Description
The Cruise Control Diagnostic System Check is an organized approach to identifying a condition created by an electronic control system failure. The Diagnostic System Check directs the service technician to the next logical step in diagnosing the concern. Understanding the system, the table, and using it correctly, reduces diagnostic time and prevents misdiagnosis. For a review of the cruise control system, refer to Cruise Control Description and Operation (4.3L) Cruise Control Description and Operation (4.8L, 5.3L, 6.0L, and 8.1L) Cruise Control Description and Operation (6.6L) .
Test Description
The numbers below refer to the step numbers on the diagnostic table.
- 2: Lack of communication may be due to a malfunction in the class 2 serial data circuit. The specified procedure will determine the particular condition.
- 5: The presence of DTCs which begin with "U" indicates that some other module is not communicating. The specified procedure will compile all the available information before tests are performed.
| Step | Action | Yes | No |
|---|---|---|---|
| 1 | Install a scan tool. Does the scan tool power up? | Go to Step 2 | Go to Scan Tool Does Not Power Up in Data Link Communications |
| 2 | Turn the ignition ON, with the engine OFF. Attempt to establish communication with the following modules: Powertrain Control Module (PCM) Electronic Brake Control Module (EBCM) Does the scan tool communicate with the modules listed above? | Go to Step 3 | Go to Scan Tool Does Not Communicate with Class 2 Device in Data Link Communications |
| 3 | IMPORTANT: The engine may start during the following step. Turn the engine OFF as soon as you have observed the Crank power mode. With a scan tool, access the Class 2 Power Mode in the Diagnostic Circuit Check. Rotate the ignition switch through all positions while observing the System Power Mode parameter. Does the System Power Mode parameter reading match the ignition switch positions for all switch positions? | Go to Step 4 | Go to Power Mode Mismatch in Body Control System |
| 4 | Select the DTCs function on the scan tool for the following modules: Powertrain Control Module (PCM) Electronic Brake Control Module (EBCM) Does the scan tool display any DTCs? | Go to Step 5 | Go to Symptoms - Cruise Control |
| 5 | Does the scan tool display any DTCs which begin with a "U"? | Go to Scan Tool Does Not Communicate with Class 2 Device in Data Link Communications | Go to Step 6 |
| 6 | Does the scan tool display DTC P0562, P0563, P0615, P0621, P0622, P1637, or P01638? | Go to Diagnostic Trouble Code (DTC) List in Engine Electrical | Go to Diagnostic Trouble Code (DTC) List |
| IMPORTANT |
|---|
| The engine may start during the following step. Turn the engine OFF as soon as you have observed the Crank power mode. |
Diagnostic System Check - Cruise Control
The numbers below refer to the step numbers on the diagnostic table.
- 2: This step determines if condition is present.
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference : Cruise Control Schematics Connector End View Reference: Cruise Control Connector End Views , Powertrain Control Module (PCM) Connector End Views in Engine Controls-4.8L, 5.3L, and 6.0L, or Powertrain Control Module (PCM) Connector End Views in Engine Controls-8.1L | |||
| 1 | Did you perform the Cruise Control Diagnostic System Check? | Go to Step 2 | Go to Diagnostic System Check - Cruise Control |
| 2 | Install a scan tool. Turn the ignition ON, with the engine OFF. Turn the cruise On/Off control switch ON. With the scan tool, observe the Cruise Resume/Accel. Switch parameter in the PCM data list. Does the Cruise Resume/Accel. Switch parameter display On? | Go to Step 3 | Go to Diagnostic Aids |
| 3 | Turn the ignition OFF. Disconnect the cruise control switch. Turn the ignition ON, with the engine OFF. With the scan tool, observe the Cruise Resume/Accel. Switch parameter. Does the Cruise Resume/Accel. Switch parameter display On? | Go to Step 4 | Go to Step 5 |
| 4 | Test the cruise control resume/accel switch signal circuit for a short to voltage. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 9 | Go to Step 6 |
| 5 | Inspect for poor connections at the harness connector of the cruise control switch. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 9 | Go to Step 8 |
| 6 | Inspect for poor connections at the harness connector of the TAC module. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 9 | Go to Step 7 |
| 7 | Replace the TAC module. Refer to the appropriate procedure: Throttle Actuator Control (TAC) Module Replacement in Engine Controls-4.8L, 5.3L, and 6.0L Throttle Actuator Control (TAC) Module Replacement in Engine Controls-8.1L Did you complete the replacement? | Go to Step 9 | |
| 8 | Replace the cruise control switch. Refer to Multifunction, Turn Signal Switch Replacement in Steering Wheel and Column. Did you complete the replacement? | Go to Step 9 | |
| 9 | Use the scan tool in order to clear the DTCs. Operate the vehicle within the Conditions for Running the DTC. Does the DTC reset? | Go to Step 2 | System OK |
DTC P0567 (4.8L, 5.3L, 6.0L, and 8.1L)
The numbers below refer to the step numbers on the diagnostic table.
- 2: This step determines if condition is present.
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference : Cruise Control Schematics Connector End View Reference: Cruise Control Connector End Views or Engine Control Module (ECM) Connector End Views in Engine Controls - 6.6L (LB7) or to Engine Control Module (ECM) Connector End Views in Engine Controls - 6.6L (LLY) | |||
| 1 | Did you perform the Cruise Control Diagnostic System Check? | Go to Step 2 | Go to Diagnostic System Check - Cruise Control |
| 2 | Install a scan tool. Turn ON the ignition, with the engine OFF. Turn the cruise On/Off control switch ON. With the scan tool, observe the Cruise Resume/Accel. Switch parameter in the PCM data list. Does the Cruise Resume/Accel. Switch parameter display On? | Go to Step 3 | Go to Diagnostic Aids |
| 3 | Turn OFF the ignition. Disconnect the cruise control switch. Turn ON the ignition, with the engine OFF. With the scan tool, observe the Cruise Resume/Accel. Switch parameter in the PCM data list. Does the Cruise Resume/Accel. Switch parameter display On? | Go to Step 4 | Go to Step 5 |
| 4 | Test the cruise control resume/accel switch signal circuit for a short to voltage. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 9 | Go to Step 6 |
| 5 | Inspect for poor connections at the harness connector of the cruise control switch. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 9 | Go to Step 7 |
| 6 | Inspect for poor connections at the harness connector of the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 9 | Go to Step 8 |
| 7 | Replace the cruise control switch. Refer to Multifunction, Turn Signal Switch Replacement in Steering Wheel and Column. Did you complete the replacement? | Go to Step 9 | |
| 8 | IMPORTANT: Program the replacement ECM. Replace the ECM. Refer to Engine Control Module (ECM) Replacement in Engine Controls - 6.6L (LB7) or to Engine Control Module (ECM) Replacement in Engine Controls - 6.6L (LLY).Did you complete the replacement? | Go to Step 9 | |
| 9 | Use the scan tool in order to clear the DTCs. Operate the vehicle within the Conditions for Running the DTC. Does the DTC reset? | Go to Step 2 | System OK |
| IMPORTANT |
|---|
| Program the replacement ECM. |
DTC P0567 (6.6L)
The number below refers to the step number on the diagnostic table.
- 2: This step determines if condition is present.
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference : Cruise Control Schematics Connector End View Reference: Cruise Control Connector End Views , Powertrain Control Module (PCM) Connector End Views in Engine Controls - 4.8L, 5.3L, and 6.0L, or Powertrain Control Module (PCM) Connector End Views in Engine Controls-8.1L | |||
| 1 | Did you perform the Cruise Control Diagnostic System Check? | Go to Step 2 | Go to Diagnostic System Check - Cruise Control |
| 2 | Install a scan tool. Turn the ignition ON, with the engine OFF. Turn the cruise On/Off control switch ON. With the scan tool, observe the Cruise Set/Coast Switch parameter in the PCM data list. Does the Cruise Set/Coast Switch parameter display On? | Go to Step 3 | Go to Diagnostic Aids |
| 3 | Turn the ignition OFF. Disconnect the cruise control switch. Turn the ignition ON, with the engine OFF. With the scan tool, observe the Cruise Set/Coast Switch parameter in the PCM data list. Does the Cruise Set/Coast Switch parameter display On? | Go to Step 4 | Go to Step 5 |
| 4 | Test the cruise control set/coast switch signal circuit for a short to voltage. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 9 | Go to Step 6 |
| 5 | Inspect for poor connections at the harness connector of the cruise control switch. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 9 | Go to Step 8 |
| 6 | Inspect for poor connections at the harness connector of the TAC module. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 9 | Go to Step 7 |
| 7 | Replace the TAC module. Refer to the appropriate procedure: Throttle Actuator Control (TAC) Module Replacement in Engine Controls-4.8L, 5.3L, and 6.0L Throttle Actuator Control (TAC) Module Replacement in Engine Controls-8.1L Did you complete the replacement? | Go to Step 9 | |
| 8 | Replace the cruise control switch. Refer to Multifunction, Turn Signal Switch Replacement in Steering Wheel and Column. Did you complete the replacement? | Go to Step 9 | |
| 9 | Use the scan tool in order to clear the DTCs. Operate the vehicle within the Conditions for Running the DTC. Does the DTC reset? | Go to Step 2 | System OK |
DTC P0568 (4.8L, 5.3L, 6.0L, and 8.1L)
The numbers below refer to the step numbers on the diagnostic table.
- 2: This step determines if condition is present.
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference : Cruise Control Schematics Connector End View Reference: Cruise Control Connector End Views or Engine Control Module (ECM) Connector End Views in Engine Controls - 6.6L (LB7) or to Engine Control Module (ECM) Connector End Views in Engine Controls - 6.6L (LLY) | |||
| 1 | Did you perform the Cruise Control Diagnostic System Check? | Go to Step 2 | Go to Diagnostic System Check - Cruise Control |
| 2 | Install a scan tool. Turn ON the ignition, with the engine OFF. Turn the cruise On/Off control switch ON. With the scan tool, observe the Cruise Set/Coast Switch parameter in the PCM Engine 1 Data, data list. Does the Cruise Set/Coast Switch parameter display On? | Go to Step 3 | Go to Diagnostic Aids |
| 3 | Turn OFF the ignition. Disconnect C1 of the ECM. Turn ON the ignition, with the engine OFF. Connect a test lamp between the cruise control set/coast switch signal circuit and a good ground. Does the test lamp illuminate? | Go to Step 4 | Go to Step 6 |
| 4 | Test the cruise control set/coast switch signal circuit for a short to voltage. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 9 | Go to Step 5 |
| 5 | Inspect for poor connections at the harness connector of the cruise control switch. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 9 | Go to Step 7 |
| 6 | Inspect for poor connections at the harness connector of the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 9 | Go to Step 8 |
| 7 | Replace the cruise control switch. Refer to Multifunction, Turn Signal Switch Replacement in Steering Wheel and Column. Did you complete the replacement? | Go to Step 9 | |
| 8 | IMPORTANT: Program the replacement ECM. Replace the ECM. Refer to Engine Control Module (ECM) Replacement in Engine Controls-6.6L (LB7) or to Engine Control Module (ECM) Connector End Views in Engine Controls - 6.6L (LLY).Did you complete the replacement? | Go to Step 9 | |
| 9 | Use the scan tool in order to clear the DTCs. Operate the vehicle within the Conditions for Running the DTC. Does the DTC reset? | Go to Step 2 | System OK |
| IMPORTANT |
|---|
| Program the replacement ECM. |
DTC P0568 (6.6L)
The numbers below refer to the step numbers on the diagnostic table.
- 8: This step tests the center high mounted stop lamp (CHMSL) supply voltage/stop lamp supply voltage circuit for an open or for a high resistance between the stop lamp switch and the throttle actuator control (TAC) module.
- 9: This step tests the cruise control set/coast switch signal circuit for an open or for a high resistance.
- 10: This step tests the cruise control resume/accel switch signal circuit for an open or for a high resistance.
- 11: This step tests the ignition 3 voltage circuit for an open, for a short to ground, or for a high resistance.
- 29: DTCs will set in the powertrain control module (PCM) when you perform this table.
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference : Cruise Control Schematics Connector End View Reference: Cruise Control Connector End Views and Powertrain Control Module (PCM) Connector End Views in Engine Controls - 4.8L, 5.3L, and 6.0L | |||
| 1 | Did you perform the Diagnostic System Check - Cruise Control? | Go to Step 2 | Go to Diagnostic System Check - Cruise Control |
| 2 | Install a scan tool. Turn the ignition ON, with the engine OFF. Turn the cruise control On/Off switch OFF. With the scan tool, observe the Cruise On/Off Switch parameter in the powertrain control module (PCM) Cruise Control Data, data list. Does the Cruise On/Off Switch parameter display Off? | Go to Step 4 | Go to Step 3 |
| 3 | Turn the ignition OFF. Disconnect C4 of the multifunction switch. Turn the ignition ON, with the engine OFF. With the scan tool, observe the Cruise On/Off Switch parameter. Does the Cruise On/Off Switch parameter display Off? | Go to Step 22 | Go to Step 13 |
| 4 | Turn the cruise control On/Off switch ON. With the scan tool, observe the Cruise On/Off Switch parameter. Does the Cruise On/Off Switch parameter display On? | Go to Step 5 | Go to Step 11 |
| 5 | With the scan tool, observe the Cruise Set/Coast Switch parameter in the PCM Cruise Control Data, data list. Turn the cruise control On/Off switch ON. Press and hold the cruise control Set/Coast button. Does the Cruise Set/Coast Switch parameter Display On? | Go to Step 6 | Go to Step 9 |
| 6 | With the scan tool, observe the Cruise Resume/Accel. Switch parameter in the PCM Cruise Control Data, data list. Press and hold the Resume/Accel switch. Does the Cruise Resume/Accel. Switch parameter Display On? | Go to Step 7 | Go to Step 10 |
| 7 | Do the stop lamps operate properly? | Go to Step 8 | Go to Stop Lamps Inoperative in Lighting Systems |
| 8 | With the scan tool, observe the Stoplamp Pedal Switch parameter in the PCM Cruise Control Data, data list. Depress and hold the brake pedal. Does the Stoplamp Pedal Switch parameter Display Applied? | Go to Diagnostic Aids | Go to Step 21 |
| 9 | Turn the ignition OFF. Disconnect the cruise control switch. Turn the ignition ON, with the engine OFF. Connect a 3-ampere fused jumper between the cruise control set/coast switch signal circuit and the ignition 3 voltage circuit. With the scan tool, observe the Cruise Set/Coast Switch parameter. Does the Cruise Set/Coast Switch parameter Display On? | Go to Step 22 | Go to Step 19 |
| 10 | Turn the ignition OFF. Disconnect the cruise control switch. Turn the ignition ON, with the engine OFF. Connect a 3-ampere fused jumper between the cruise control resume/accel switch signal circuit and the ignition 3 voltage circuit. With the scan tool, observe the Cruise Resume/Accel. Switch parameter. Does the Cruise Resume/Accel. Switch parameter Display On? | Go to Step 22 | Go to Step 20 |
| 11 | Turn the ignition OFF. Disconnect the cruise control switch. Turn the ignition ON, with the engine OFF. Connect a test lamp between the ignition 3 voltage circuit and a good ground. Does the test lamp illuminate? | Go to Step 12 | Go to Step 15 |
| 12 | Connect a 3-ampere fused jumper between the ignition 3 voltage circuit and the cruise control on switch signal circuit. With the scan tool, observe the Cruise On/Off Switch parameter. Does the Cruise On/Off Switch parameter display On? | Go to Step 22 | Go to Step 18 |
| 13 | Test the cruise control on switch signal circuit for a short to voltage. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 29 | Go to Step 14 |
| 14 | Turn the ignition OFF. Disconnect C1 of the throttle actuator control (TAC) module. Turn the ignition ON, with the engine OFF. With the scan tool, observe the Cruise On/Off Switch parameter. Does the Cruise On/Off Switch parameter display On? | Go to Step 24 | Go to Step 23 |
| 15 | Test the cruise control set/coast switch signal circuit for a short to ground. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 29 | Go to Step 16 |
| 16 | Test the cruise control resume/accel switch signal circuit for a short to ground. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 29 | Go to Step 17 |
| 17 | Test the cruise control on switch signal circuit for a short to ground. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 29 | Go to Step 25 |
| 18 | Test the cruise control on switch signal circuit for an open or for a high resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 29 | Go to Step 23 |
| 19 | Test the cruise control set/coast switch signal circuit for an open or for a high resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 29 | Go to Step 23 |
| 20 | Test the cruise control resume/accel switch signal circuit for an open or for a high resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 29 | Go to Step 23 |
| 21 | Test the center high mounted stop lamp (CHMSL) supply voltage/stop lamp supply voltage circuit for an open or for a high resistance between the stop lamp switch and the TAC module. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 29 | Go to Step 23 |
| 22 | Inspect for poor connections at the harness connector of the cruise control switch. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 29 | Go to Step 26 |
| 23 | Inspect for poor connections at the harness connector of the TAC module. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 29 | Go to Step 27 |
| 24 | Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 29 | Go to Step 28 |
| 25 | Repair the open, the high resistance, or the short to ground in the ignition 3 voltage circuit. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 29 | |
| 26 | Replace the cruise control switch. Refer to Multifunction, Turn Signal Switch Replacement in Steering Wheel and Column. Did you complete the replacement? | Go to Step 29 | |
| 27 | Replace the TAC module. Refer to Throttle Actuator Control (TAC) Module Replacement in Engine Controls - 4.8L, 5.3L, and 6.0L or to Throttle Actuator Control (TAC) Module Replacement in Engine Controls - 8.1L. Did you complete the replacement? | Go to Step 29 | |
| 28 | IMPORTANT: Program the replacement PCM. Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement in Engine Controls - 4.8L, 5.3L, and 6.0L or to Powertrain Control Module (PCM) Replacement in Engine Controls - 8.1L.Did you complete the replacement? | Go to Step 29 | |
| 29 | Use the scan tool in order to clear the PCM DTCs. Operate the vehicle within the conditions for cruise control operation. Does the cruise control system operate properly? | System OK | Go to Step 2 |
| IMPORTANT |
|---|
| Program the replacement PCM. |
Cruise Control Inoperative/Malfunctioning (4.8L, 5.3L, 6.0L, 8.1L)
Cruise Control Description and Operation (4.3L)
Cruise control is a speed control system that maintains a desired vehicle speed under normal driving conditions at vehicle speeds above 40 km/h (25 mph). Steep grades may cause variations in the selected vehicle speeds.
The following are the main components of the cruise control system
- The powertrain control module (PCM)
- The On/Off switch
- The Resume/Accel. Switch
- The Set/Coast Switch
- The stop lamp switch
- The torque converter clutch (TCC) brake switch
- The cruise control module
- The clutch pedal position (CCP) switch, if equipped with a manual transmission
- The vehicle speed sensor
Cruise Control Description and Operation (4.8L, 5.3L, 6.0L, and 8.1L)
Cruise control is a speed control system that maintains a desired vehicle speed under normal driving conditions at vehicle speeds above 40 km/h (25 mph). Steep grades may cause variations in the selected vehicle speeds.
The following are the main components of the Cruise Control System
- The powertrain control module (PCM)
- The On/Off switch
- The Resume/Accel switch
- The Set/Coast switch
- The TCC/brake switch
- The stop lamp switch
- The throttle actuator control (TAC) module
- The Clutch Pedal Position (CPP) switch, if equipped with a manual transmission
- The vehicle speed sensor (VSS)
Cruise Control Description and Operation (6.6L)
Cruise control is a speed control system that maintains a desired vehicle speed under normal driving conditions at vehicle speeds above 40 km/h (25 mph). Steep grades may cause variations in the selected vehicle speeds.
The following are the main components of the cruise control system
- The engine control module (ECM)
- The On/Off switch
- The Resume/Accel. Switch
- The Set/Coast Switch
- The TCC/Brake Switch
- The clutch pedal position (CPP) switch, if equipped with a manual transmission.
- The vehicle speed sensor