Circuit/System Testing
WARNING: This page is about a different car, the 2008 GMC Sierra and 2008 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
IMPORTANT:
All electrical components and accessories must be turned OFF and allowed to power down.
- Ignition OFF, disconnect the ECT harness connector at the ECT sensor.
- Ignition OFF for 90 seconds, test for less than 5 ohms between the low reference circuit pin A and ground.
- If greater than the specified range, test the low reference circuit pin A for an open/high resistance. If the circuit tests normal, replace the ECM.
- Ignition ON, verify the scan tool ECT Sensor parameter is less than -39°C (-38°F).
- If greater than the specified range, test the signal circuit pin B for a short to ground. If the circuit tests normal, replace the ECM.
- Install a 3A fused jumper wire between the signal circuit pin B and the low reference circuit. Verify the scan tool ECT Sensor parameter is greater than 149°C (300°F).
- If less than the specified range, test the signal circuit pin B 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 ECT sensor.