Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the ECT sensor.
- Ignition OFF, remove the fuse that supplies B+ to circuit terminal X2-56 of the ECM.
- Test for less than 5 Ω between the low reference circuit terminal 2 and ground.
- If greater than specified value, test the circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.
- Install the fuse that supplies B+ to circuit terminal X2-56 of the ECM.
- Ignition ON, observe the scan tool the ECT sensor parameter. Verify that the ECT sensor parameter is at -40°C (-40°F).
- If warmer than the specified value, test the signal circuit for a short to ground. If the circuit/connections test normal, replace the ECM.
- Install a 3 A fused jumper wire between the signal circuit terminal 1 and the low reference circuit terminal 2. Verify the scan tool ECT sensor parameter is warmer than 142°C (288°F).
- If colder than the specified value, test the signal circuit for an open/high resistance or for a short to voltage. If the circuit/connections test normal, replace the ECM.
- If all circuits test normal, test or replace the ECT sensor.
CAUTION:
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.
NOTE:
The control module or the sensor may be damaged if the circuit is shorted to battery positive voltage.
NOTE:
If the fuse in the jumper wire opens, the signal circuit is shorted to a voltage and the ECT sensor may be damaged.