High Idle Switch Diagnosis

High Idle Switch Diagnosis

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions)provide an overview of each diagnostic category.

Diagnostic Fault Information





Reference Information
Schematic Reference

Engine Controls Schematics ([1][2]Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector End Views By Name)
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

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.