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Home >> GMC >> 2006 >> Sierra 1500 HD, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1044 (Engine Controls And Fuel - 4.8L, 5.3L, 6.0L, 6.2L, Or 7.0L - DTC P0010 To DTC P0230) >> DTC P0191 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2008 GMC Sierra, 2008 GMC Cab & Chassis Sierra, 2008 Chevrolet Silverado, and 2008 Chevrolet Cab & Chassis Silverado. 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 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. Verify the scan tool fuel rail pressure volts parameter is less than 1 V.
    • If greater than the specified range, test the signal circuit terminal 1 for a short to voltage. If the circuit tests normal, replace the fuel pump flow control module.
  5. Install a 3 A fused jumper wire between the signal circuit terminal 1 and the 5 V reference circuit terminal 3. Verify the scan tool fuel rail pressure sensor volts parameter is greater than 4.8 V.
    • 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 fuel pump flow control module.
  6. If all circuits test normal, replace the fuel rail pressure sensor.
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