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Home >> GMC >> 2006 >> Sierra 1500 HD, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 865 (Instrument Panel System Displays And Gauges) >> Diagnostic Information & Procedures >> Fuel Gauge Inaccurate or Inoperative (Dual Tanks) >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2007 GMC Sierra and 2007 Chevrolet 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 primary and secondary fuel level sensors. Jumper the 2 signal circuits together and then install a signal generator and instrument panel tester between the signal circuits and the low reference circuit.
  2. Ignition ON, vary the resistance on the signal generator from 40-250 ohms. Verify that the scan tool Fuel Tank Level Remaining parameter displays the correct fuel level percent.
    • If the fuel level percent is incorrect, test both signal circuits and the low reference circuit for an open/high resistance. If the circuits test normal, replace the ECM.
  3. Ignition ON, vary the resistance on the signal generator from 40-250 ohms and monitor the fuel gauge.
    • If the gauge is incorrect, replace the IPC.
  4. If all circuits test normal, test or replace either the primary or secondary fuel level sensor.
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