Circuit/System Testing
WARNING: This page is about a different car, the 2009 GMC Sierra, 2009 GMC Cab & Chassis Sierra, 2009 Chevrolet Silverado, and 2009 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition OFF, disconnect the harness connector at the mass air flow MAF/IAT sensor.
- Ignition OFF and scan tool disconnected for 90 seconds, test for less than 5 Ω between the IAT Sensor 1 low reference circuit terminal 4 and ground.
- If greater than the specified range, test the IAT Sensor 1 low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
- Ignition OFF and scan tool disconnected for 90 seconds, test for less than 5 Ω between the MAF sensor low reference circuit terminal 2 and ground.
- If greater than the specified range, test the MAF sensor low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
- Ignition ON, verify the scan tool IAT Sensor 1 parameter is colder than -39°C (-38°F).
- If warmer than the specified range, test the signal circuit terminal 5 for a short to ground. If the circuit tests normal, replace the ECM.
- Install a 3A fused jumper wire between the signal circuit terminal 5 and a ground. Verify the scan tool IAT Sensor 1 parameter is warmer than 148°C (298°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 ECM.
- If all circuits test normal, test or replace the MAF/IAT sensor.
NOTE:
If a short to voltage is found on the IAT signal circuit, the 3A fuse in the jumper wire will open.