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.
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)
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 in Cruise Control Description and Operation (Description and Operation) .
Circuit/System Testing
1. Ignition ON, at the back of the column harness connector X204 terminal A8, measure for 10 volts or greater on the cruise control supply voltage circuit.
• If less than the specified value, test the cruise control supply voltage circuit for an open/high resistance or a short to ground.
2. Ignition OFF, disconnect column harness connector X204.
3. Ignition ON, verify a test lamp illuminates between B+ and the cruise control switch signal circuit connector X204 terminal B8 on the body side of the harness.
• If the test lamp does not illuminate, test the cruise control switch signal circuit for an open/high resistance or a short to voltage. If the circuit tests normal, replace the ECM.
4. Ignition OFF, disconnect the harness connector X1 at the ECM.
5. Verify that a test lamp does not illuminate between B+ and the cruise control switch signal circuit connector X204 terminal B8 on the body side of the harness.
• If the test lamp illuminates, test the cruise control switch signal circuit for a short to ground.
6. If all circuits test normal, test the component. If the circuits and the component tests are 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, disconnect the steering column harness connector X204.
2. Ignition ON, cruise control switch ON, measure the resistance between terminals A8 and B8 on the cruise control switch side of the connector. 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 switch assembly.
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 replacement, setup, and programming