Circuit/System Testing
- Ignition OFF, disconnect 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 OFF, remove the ECM/TCM fuse from the underhood fuse block.
- Test for less than 5 ohms between the low reference circuit and the ECM housing.
- If greater than 5 ohms, test the low reference circuit for an open/high resistance, or for a short to voltage. If the circuit/connections test normal, replace the ECM.
- Ignition OFF, install the ECM/TCM fuse to the underhood fuse block.
- Ignition ON, install a 3-amp fused jumper wire between the signal circuit and the low reference circuit of the ECT sensor and verify the ECT sensor parameter is greater than 142°C (288°F).
- If less than 143°C (289°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.
NOTE:
Do NOT use a test lamp to test the continuity of the circuit. Damage to the control module may occur due to excessive current draw.
IMPORTANT:
The control module or the sensor may be damaged if the circuit is shorted to battery positive voltage.