High Idle Switch Diagnosis

High Idle Switch Diagnosis

Diagnostic Instructions

* Perform theDiagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* ReviewStrategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview)provide an overview of each diagnostic category.



Diagnostic Fault Information






Reference Information
Schematic Reference

Engine Controls Schematics (Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector Views)
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, observe the scan tool High Idle switch parameter while exercising the switch. The reading should change between ON/OFF.


Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the high idle switch.
2. Test for less than 5 ohms between the ground circuit terminal A and ground.

• If greater than 5 ohms, test the ground circuit for an open/high resistance.

3. Ignition ON, verify the scan tool High Idle switch parameter is OFF.

• If not OFF, test the signal circuit for a short to ground. If the circuit tests normal, replace the ECM.

4. Install a 3A fused jumper wire between the signal circuit terminal C and ground. Verify the scan tool High Idle switch parameter is ON.

• If not ON, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.

5. If all circuits test normal, test or replace the high idle switch.



Component Testing

1. Ignition OFF, disconnect the harness connector at the high idle switch.
2. Test for infinite resistance between the signal terminal C and the ground circuit terminal A with the switch in the open position.

• If less than infinite resistance, replace the high idle switch.

3. Test for less than 1 ohm between the signal terminal C and the ground terminal A with the switch in the closed position.

• If greater than 1 ohm, replace the high idle switch.