Cruise Control Malfunction
Cruise Control Malfunction
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.
Diagnostic Fault Information
Circuit/System Description
The cruise control switch is an input to the engine control module (ECM). The ECM monitors the cruise control switch signal circuit in order to detect when a cruise control function has been requested. The ECM detects a specific voltage signal on the cruise control switch signal circuit when a cruise control function switch is activated, with each switch having a different predetermined voltage value. The BCM monitors the cruise control cancel switch signal circuit and also sends a serial data message to the ECM indicating the status of the cruise cancel switch.
Diagnostic Aids
Important: Repair any brake system related symptoms or DTCs before performing this diagnostic.
In order to avoid misdiagnosis, inspect for the following:
* Verify there are no DTCs set as current. If any DTCs are set as current, Refer to Diagnostic Trouble Code (DTC) List - Vehicle (Diagnostic Trouble Code Descriptions) and perform the appropriate diagnostics/repairs before proceeding with symptom based diagnostics.
* Inspect the cruise control switches for any sticking or binding conditions.
* Inspect for proper operation of the stop lamps. Refer to Exterior Lighting Systems Description and Operation (Exterior Lighting Systems Description and Operation).
* Electromagnetic interference (EMI) on the speed sensor signal circuit may cause erratic cruise control operation.
Reference Information
Schematic Reference
Cruise Control Schematics (Electrical Diagrams)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
Cruise Control Description and Operation (Description and Operation)
Electrical Information Reference
* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Circuit/System Verification
Ignition ON, cruise on/off switch ON. With a scan tool, observe all cruise control switch parameters in the ECM. Verify that the displayed switch position parameters match accordingly for each depressed switch. Road test the vehicle to ensure the cruise control system functions as described inCruise Control Description and Operation (Description and Operation).
Circuit/System Testing
1. Ignition OFF, disable the SIR system. Refer to SIR Disabling and Enabling (Service and Repair).
2. Disconnect the harness connector at the cruise control lever.
3. Ignition ON, measure for 10 volts or greater at the supply voltage circuit terminal 2.
• If less than the specified value, test the supply voltage circuit for a short to ground or an open/high resistance.
4. Verify the scan tool Cruise On/Off Switch parameter is OFF.
• If not the specified value, test the signal circuit terminal 1 for a short to voltage. If the circuit tests normal, replace the ECM.
5. Verify the scan tool Cruise Cancel Switch parameter reads Inactive.
• If not the specified value, test the signal circuit terminal 3 for a short to voltage. If the circuit tests normal, replace the BCM.
6. Ignition OFF, connect the harness connector at the cruise control lever.
7. Ignition ON, observe the scan tool Cruise Cancel Switch parameter while pressing the Cancel portion of the cruise control lever. The parameter should display Active.
• If not the specified value, test the signal circuit terminal 3 for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the cruise control lever.
8. Ignition ON, with the cruise control switch in the ON position, observe the scan tool Cruise On/Off Switch parameter. The parameter should display ON.
• If not the specified value, test the signal circuit terminal 1 for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the cruise control lever.
9. Observe the scan tool Cruise Resume/Accel. Switch parameter while pressing the RES + portion of the cruise control lever. The parameter should display Active.
• If not the specified value, test or replace the cruise control lever.
10. Observe the scan tool Cruise Set/Coast Switch parameter while pressing the SET - portion of the cruise control lever. The parameter should display Active.
• If not the specified value, test or replace the cruise control lever.
11. If the circuits test normal, replace the ECM.
Component Testing
Important: The cruise control switch must be ON in order to properly measure the resistance of the set/cruise and the resume/accel switches.
1. Ignition OFF, disable the SIR system. Refer to SIR Disabling and Enabling (Service and Repair).
2. Disconnect the harness connector of the cruise control lever.
3. Cruise control switch ON, measure the resistance between terminals 1 and 2 at the cruise control lever side of the connector (terminals 2 and 3 for the cancel switch). Individually activate and hold each cruise control function switch and compare the resistance reading to the values in the table for the appropriate switch.
• If any resistance measurements for any of the switches are not within the listed resistance values, replace the cruise control lever.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Turn Signal Multifunction Switch Replacement (Turn Signal Multifunction Switch Replacement)
* Control Module References (Programming and Relearning) for ECM or BCM replacement, setup, and programming