P0568
DTC P0568
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.
DTC Descriptor
DTC P0568
- Cruise Control Set Switch Circuit
Diagnostic Fault Information
Circuit/System Description
The cruise control switch is an input to the body control module (BCM) and to the engine control module (ECM) with (LS4/LY7), or the powertrain control module (PCM) with (L26). The BCM monitors the cancel switch, and the ECM/PCM monitors the cruise control ON/OFF, Set/Coast, and the Resume/Accel. switch signal circuits in order to detect when a cruise control function switch has been activated. The ECM/PCM detects a predetermined voltage signal when a cruise control function switch is applied, with each switch having a different voltage value.
Conditions for Running the DTC
* The ignition is ON.
* The cruise switch is ON.
Conditions for Setting the DTC
The ECM/PCM detects that the Set/Coast switch is applied for longer than 90 seconds.
Actions Taken When the DTC Sets
* The malfunction indicator lamp (MIL) will not illuminate.
* The cruise control system is disabled.
Conditions for Clearing the DTC
* The condition responsible for setting the DTC no longer exists.
* A history DTC will clear after 40 malfunction-free ignition cycles have occurred.
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
Engine ON, while rotating the steering wheel to both steering stops, observe the scan tool Cruise Control Switch parameter while pressing each of the cruise control switches. The parameter should toggle between ON, OFF, Resume and Set as the applicable switch is pressed.
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the steering wheel controls switch - left.
2. Ignition OFF, test for less than 10 ohms between the ground circuit terminal 8 and ground.
• If greater than the specified range, test the ground circuit for an open/high resistance.
3. Ignition ON, test for B+ between the ignition voltage circuit terminal 1 and ground.
• If less than the specified value, test the ignition voltage circuit for a short to ground or an open/high resistance.
4. Ignition ON, test for B+ between the ignition voltage circuit terminal 1 and cruise control cancel switch terminal 5.
• If less than the specified range, test the cruise control cancel circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
5. Verify the scan tool Cruise ON/OFF switch parameter displays OFF.
• If not the specified value, test the signal circuit terminal 3 for a short to voltage. If the circuit tests normal, replace the ECM with (LS4/LY7), or PCM with (L26).
6. Install a 3A fused jumper wire between the signal circuit terminal 3 and the ignition voltage circuit terminal 1. Verify the scan tool Cruise ON/OFF Switch parameter displays ON.
• If not the specified value, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM with (LS4/LY7), or PCM with (L26).
7. If all circuits test normal, test or replace the steering wheel controls switch - left.
Component Testing
Important: The cruise control switch must be ON in order to properly measure the resistance of the - /SET, and +/RES, switches.
1. Disconnect the harness connector at the steering wheel control switch-left.
2. Connect a DMM between terminals 1 and 3 signal circuit or terminals 1 and 5 for the cancel switch circuit of the steering wheel control switch-left.
3. Cruise control switch ON, measure the resistance while individually activating and holding each cruise control function switches and compare the resistance reading to the values in the table for the appropriate switch.
• If any of the resistance measurements for the individual switches are not within the specified resistance values, replace the steering wheel control switch-left.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Steering Wheel Control Switch Assembly Replacement (Service and Repair)
* Control Module References (Programming and Relearning) for ECM or PCM replacement, setup, and programming