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Home >> Hummer >> 2008 >> H2 4D Utility Wagon >> Repair and Diagnosis >> External Pages >> Different car >> Section 247 (Engine Control System & Fuel - 4.8L, 5.3L, 6.0L, Or 6.2L - DTC P0010 To DTC P0230) >> DTC P0191 >> Circuit/System Testing

Circuit/System Testing

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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.
  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 rail pressure sensor.
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