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Home >> Hummer >> 2009 >> H3 Alpha >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls And Fuel - 5.3L - DTC P0016 To DTC P0308 >> DTC P0191 >> Circuit/System Testing
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Circuit/System Testing

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 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 fuel pump flow control module.
  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 fuel pump flow control module.
    • If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the fuel pump flow control module.
  4. Ignition OFF, install a 3A fused jumper wire between the 5-volt reference circuit terminal 3 and the signal circuit terminal 1.
  5. Ignition ON, observe the Fuel Pump Control Module Fuel Rail Pressure Sensor parameter. 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 fuel pump flow control module.
  6. If all circuits test normal, replace the fuel pressure sensor.
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