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HOMESERVICE MANUALSCHEVROLET2003TRAILBLAZER 4.2 S, 4WDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 1936 (ENGINE CONTROLS AND FUEL - 3.5L - DTC P0010 TO DTC P0232)DTC P0191 (FPCM)CIRCUIT/SYSTEM TESTING (FPCM)
2003 Chevrolet TrailBlazer 4.2 S, 4WD

Circuit/System Testing (FPCM)

2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Circuit/System Testing (FPCM)
WARNING: This page is about a different car, the 2009 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
IMPORTANT: Verify that the fuel tank is not empty. Only perform this diagnostic if there is at least 2 gallons of fuel in the fuel tank. Clear the DTC, and start and run the engine. Verify that the DTC P0191 resets before proceeding with the circuit system testing. If the DTC does not reset, refer to diagnostic aids.
  1. Ignition OFF, disconnect the harness connector at the fuel line pressure sensor.
  2. Ignition OFF, test for less than 1.0 ohm between the low reference circuit terminal 2 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 FPCM.
  3. Ignition ON, test for 4.8-5.2 volts between the fuel line pressure sensor 5-volt reference circuit terminal 3 and ground.
    • If less than the specified range, test the 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the FPCM.
    • If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the FPCM.
  4. Ignition ON, observe the Fuel Pump Control Module Fuel Rail Pressure Sensor parameter.
  5. Install a 3A fused jumper wire between the 5-volt reference circuit terminal 3 and the fuel line pressure sensor signal circuit terminal 1. The scan tool should display between 4.8-5.2 volts.
    • If less than the specified range, test the signal circuit terminal 1 for a short to ground or an open/high resistance. If the circuit tests normal, replace the FPCM.
    • If greater than the specified range, test the signal circuit terminal 1 for a short to voltage. If the circuit tests normal, replace the FPCM.
  6. If all circuits test normal, replace the fuel pressure sensor.
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