Circuit/System Testing
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2012 GMC Yukon XL, 2012 GMC Yukon, 2012 Chevrolet Tahoe, 2012 Chevrolet Suburban, and 2012 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition OFF, disconnect the harness connector at the primary and secondary fuel level sensors.
- Ignition OFF, test for less than 1.0 Ω between the primary fuel level sensor low reference circuit terminal B 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 ECM.
- Ignition OFF, test for less than 1.0 Ω between the secondary fuel level sensor low reference circuit terminal B 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 ECM.
- Jumper the primary fuel level sensor signal circuit terminal C to secondary fuel level sensor signal circuit terminal C. Install a signal generator and instrument panel tester between the jumped signal circuits and ground.
- Ignition ON, vary the signal generator resistance between 40-250 Ω. Verify that the scan tool Fuel Tank Level Remaining parameter displays a range that varies between 5 and 95 percent as the signal generator resistance changes.
- If not within the specified range, test both signal circuits for an open/high resistance. If the circuits test normal, replace the ECM.
- Vary the signal generator resistance between 40-250 Ω. Verify that the fuel gauge displays a range that varies between empty and full as the signal generator resistance changes.
- If the gauge is incorrect, replace the IPC.
- If all circuits test normal, perform the fuel level sensor component test before replacing either the primary or secondary fuel level sensor.