Circuit/System Testing
- Ignition ON, observe the ECT sensor parameter with a scan tool while moving the ECT sensor harness and connector, and the harness and connector. The ECT sensor parameter should not fluctuate while moving the related harnesses and connectors.
- If the ECT sensor value fluctuates while moving the harness, repair the appropriate harness/connector.
- Ignition OFF, disconnect the harness connector of the ECT sensor.
- Ignition ON, verify that the ECT sensor parameter is at -40°C (-40°F).
- If greater than -40°C (-40°F), test the signal circuit of the ECT sensor for a short to ground. If the circuit/connections test normal, replace the ECM.
- Ignition ON, install a 3-amp fused jumper wire between the signal circuit and the low reference circuit of the ECT sensor. Verify the ECT sensor parameter is greater than 132°C (270°F).
- If less than 132°C (270°F), test the signal circuit of the ECT sensor for a short to voltage or an open/high resistance. If the circuit/connections test normal, replace the ECM.
- If all circuits/connections test normal, test or replace the ECT sensor.