Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the IAT sensor.
- Ignition ON, clear the DTC information with a scan tool.
- Ignition ON, verify that the scan tool IAT sensor parameter is at -40°C (-40°F).
- If greater than the specified value, test the signal circuit for a short to ground. If the circuit/connections test normal, replace the ECM.
- Test for less than 0.5 volt between the low reference circuit and ground.
- If greater than the specified value, test the low reference circuit for a short to voltage. If the circuit/connections test normal, replace the ECM.
- Ignition OFF, test for less than 5 ohms of resistance between the low reference circuit and ground.
- If greater than the specified value, test the low reference circuit for an open/high resistance. If the circuit/connections test normal, replace the ECM.
- Ignition ON, clear the DTC information with a scan tool.
- Install a 1A fused jumper wire between the signal circuit and the low reference circuit. Verify the IAT sensor parameter is greater than 135°C (275°F).
- If less than the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit/connections test normal, replace the ECM.
IMPORTANT: If the fuse in the jumper wire opens, the signal circuit is shorted to a voltage and the sensor may be damaged. - If all circuits/connections test normal, test or replace the IAT sensor.