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Home >> Chevrolet >> 2014 >> Express 1500 LS, AWD >> Repair and Diagnosis >> Accessories & Equipment >> Gauges & Instrument Panels >> Instrument Panel System Displays And Gauges >> Diagnostic Information and Procedures >> DTC P0461-P0464: Fuel Level Sensor 1 (with LC8 and FHZ) >> Circuit/System Testing

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the alternative fuel tank pressure sensor.
  2. Ignition OFF and all vehicle systems OFF. It may take up to 2 minutes for all vehicle systems to power down. Test for less than 10Ω between the low reference circuit terminal 1 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 CNGCM.
  3. Remove Fuel Pump Relay 38. Install a 30A fused jumper wire between fuel pump relay connector terminals 30 to 87. Ignition ON.
  4. Test for 4.8-5.2 V between the 5 V reference circuit terminal 3 and ground.
    • If less than the specified range, test the 5 V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the CNGCM.
    • If greater than the specified range, test the 5 V reference circuit for a short to voltage. If the circuit tests normal, replace the CNGCM.
  5. Install a 3A fused jumper wire at the signal circuit terminal 2. Toggle the jumper wire between the low reference circuit terminal 1 and the 5V reference circuit terminal 3. Verify the fuel gauge toggles between full and empty.
    • If the fuel gauge does not toggle between full and empty, test the signal circuit for a short to voltage, short to ground or an open/high resistance.
  6. Ignition OFF, remove 30A fused jumper wire between fuel pump relay connector terminals 30 to 87, connect the harness connector at the alternative fuel tank pressure sensor.
  7. Disconnect the X2 harness connector at the CNGCM, install a 30A fused jumper wire between fuel pump relay connector terminals 30 to 87.
  8. Ignition ON, test for 4.0-6.0V between the signal circuit terminal B and ground.
    • If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
    • If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.
  9. If all circuits test normal, replace the alternative fuel tank pressure sensor.
  10. If the fuel gauge is still malfunctioning, replace the CNGCM.
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