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Home >> Chevrolet >> 2011 >> Chevy Express G2500, Van Cargo Extended, 6.6 L >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls And Fuel - 6.6L (LGH) - DTC P0016 Through DTC P11DC >> Diagnostic Information and Procedures >> DTC P0191 >> Testing >> Circuit/System Testing

Circuit/System Testing

NOTE:
  • You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.
  • Review Freeze Frame Data to determine which operating mode the DTC was set.
  • If Post Drive Mode fails, engine will go to Reduced Power Mode the next key cycle.
  • Improper Fuel Pressure Regulator 2 torque may cause this DTC to set.

Post Drive Mode Testing

  1. Ignition OFF, open a fuel injector high pressure fuel line.
  2. Ignition ON, verify the scan tool Fuel Pressure Sensor Voltage parameter is between 0.352-0.65 V.
    • If less than the specified range, test the Fuel Rail Pressure Sensor Signal circuit and the Fuel Rail Pressure Sensor 5 Volt Reference circuit for high resistance. If the circuit tests normal, replace the B47B fuel rail pressure sensor.
    • If greater than the specified range, test Fuel Rail Pressure Sensor Low Reference circuit for high resistance. If the circuit tests normal, replace the B47B fuel rail pressure sensor.
  3. Install the fuel injector high pressure line.
  4. Engine running for 2 minutes.
    5. NOTE:

    Contaminated fuel could cause fuel pressure regulator 2 to hold rail pressure during key OFF.

  5. Ignition OFF, wait 30 s, verify the scan tool Fuel Pressure Sensor Voltage parameter is less than 0.65 V.
    • If the Fuel Pressure Voltage parameter is greater than the specified value, replace the Q18B fuel pressure regulator 2.
  6. Engine at idle, command the fuel pressure incrementally through the entire fuel pressure range with a scan tool. The Actual Fuel Rail Pressure and the Desired Fuel Rail Pressure should be within 690 kPa (100 psi) for the entire fuel pressure range.
    • If not within the specified range, replace the Q18B fuel pressure regulator 2.
  7. If the system tests normal, refer to Diagnostic Aids above.

Idle Mode Testing

  1. Engine at idle and normal operating temperature.
  2. Command the fuel pressure incrementally through the entire fuel pressure range with a scan tool. The Actual Fuel Rail Pressure and the Desired Fuel Rail Pressure should be within 690 kPa (100 psi) for the entire fuel pressure range.
    • If not within the specified range, replace the Q18B fuel pressure regulator 2.
  3. Ignition OFF, disconnect the harness connector at the Q18B fuel pressure regulator 2.
  4. Connect a DMM between the fuel pressure regulator 2 harness connector terminal 1 and the fuel pressure regulator 2 terminal 1.
  5. Connect a jumper wire between the fuel pressure regulator 2 harness connector terminal 2 and the fuel pressure regulator 2 terminal 2.
    6. NOTE:

    Refer to Typical Fuel Pressure Regulator 2 Idle Current table for service limits in Diagnostic Aids above.

  6. Engine at stable idle, verify the fuel pressure regulator 2 current is between 185-969 mA.
    • If the current is less than 185 mA, inspect for contaminates in the fuel pressure regulator 2 filter screen. If contaminates are present, refer to Contaminants-in-Fuel Diagnosis . If no contaminates are present, replace the Q18B fuel pressure regulator 2.
    • If current is greater than 969 mA, verify the fuel pressure regulator 2 is properly torqued. If properly torqued, replace the Q18B fuel pressure regulator 2.

      Verify DTC does not reset. If DTC resets, refer to Fuel System Diagnosis - High Pressure Side .

  7. Ignition ON, verify the scan tool Fuel Pressure Sensor Voltage parameter is between 0.352-0.65 V.
    • If less than the specified range, test the Fuel Rail Pressure Sensor Signal circuit and the Fuel Rail Pressure Sensor 5 Volt Reference circuit for high resistance. If the circuit tests normal, replace the B47B fuel rail pressure sensor.
    • If greater than the specified range, test Fuel Rail Pressure Sensor Low Reference circuit for high resistance. If the circuit tests normal, replace the B47B fuel rail pressure sensor.
    • If within the specified range, refer to Diagnostic Aids above.
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