Circuit/System Testing
- Ignition OFF, disconnect the ECT harness connector at the ECT sensor.
- Ignition OFF for 90 seconds, test for less than 5 ohms of resistance between the low reference circuit and ground.
- If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
- Ignition ON, verify the scan tool ECT Sensor parameter is less than -39°C (-38°F).
- If greater than the specified range, test the signal circuit for a short to ground. If the circuit tests normal, replace the ECM.
- Install a 3A fused jumper wire between the signal circuit and the low reference circuit. Verify the scan tool ECT Sensor parameter is greater than 140°C (284°F).
- If less than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.
- If the circuits test normal, test the ECT sensor.