Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the B75B MAF/IAT sensor.
- Ignition OFF for 90 s, test for less than 5 Ω between the low reference circuit terminal D 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 K20 ECM.
- Ignition ON, verify the scan tool IAT Sensor parameter is colder than -39°C (-38°F).
- If warmer than the specified range, test the signal circuit terminal E for a short to ground. If the circuit tests normal, replace the K20 ECM.
- Install a 3 A fused jumper wire between the signal circuit terminal E and ground. Verify the scan tool IAT Sensor parameter is warmer than 149°C (300°F).
- If colder 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 K20 ECM.
- If the circuits test normal, test or replace the B66 IAT sensor.