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Home >> GMC >> 2006 >> Sierra 1500 HD, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 985 (Instrument Panel System Displays & Gages) >> Diagnostic Information and Procedures >> Fuel Gage Inaccurate or Inoperative (Single Tank) >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2008 GMC Sierra, 2008 GMC Cab & Chassis Sierra, 2008 Chevrolet Silverado, and 2008 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the harness connector at the fuel level sensor.
  2. Ignition OFF, test for less than 1.0 ohm between the 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.
  3. Install a Signal Generator and Instrument Panel Tester between the signal circuit terminal C and ground.
  4. Ignition ON, vary the signal generator resistance between 40-250 ohms. 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 the signal circuit for an open/high resistance. If the circuits test normal, replace the ECM.
  5. Vary the signal generator resistance between 40-250 ohms. Verify that the fuel gage displays a range that varies between empty and full as the signal generator resistance changes.
    • If the gage is incorrect, replace the IPC.
  6. If all circuits test normal, perform the fuel level sensor component test before replacing the fuel level sensor.
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