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Home >> Hummer >> 2008 >> H2 4D Utility Wagon >> Repair and Diagnosis >> External Pages >> Different car >> Section 187 (Instrument Panel System Displays & Gages) >> Diagnostic Information and Procedures >> Fuel Gage Inaccurate or Inoperative (Single Tank) >> Circuit/System Testing

Circuit/System Testing

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  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 5-95 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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