Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the ECT sensor.
- Ignition ON, clear the DTC information with a scan tool.
- Ignition ON, using a scan tool 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 tests normal, replace the ECM.
- Test for less than 0.5 volt between the low reference circuit and ground.
- If greater than specified value, test the low reference circuit for a short to voltage. If the circuit tests normal, replace the ECM.
- Ignition OFF, test for less than 5 ohms of resistance between the low reference circuit and ground.
- If greater than 5 ohms, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
- Ignition ON, clear the DTC information with a scan tool.
- Install a 1-amp fused jumper wire between the signal circuit and the low reference circuit. Verify the ECT sensor parameter is greater than 128°C (262°F).
- If less than 128°C (262°F), test the signal circuit of the ECT sensor for a short to voltage or an open/high resistance. If the circuit test normal, replace the ECM.
- If all circuits test normal, test or replace the ECT sensor.
IMPORTANT:
If the signal circuit is shorted to voltage the ECT sensor may be damaged.