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Tahoe / Yukon Service Manual

DTC P228A or P228B

Engine Controls and Fuel - 3.0L LM2 Diesel | Diagnostic Information and Procedures | Document ID: 5398973 Diagnostic Instructions Perform the Diagnostic System Check prior to using this diagnostic procedure: Diagnostic System Check - Vehicle Review the description of Strategy Based Diagnosis: Strategy Based Diagnosis An overview of each diagnostic category can be found here: Diagnostic Procedure Instructions DTC Descriptor DTC P228A Fuel Pressure Regulator Control - Forced Engine Shutdown DTC P228B Fuel Pressure Regulator 2 Control - Forced Engine Shutdown Circuit/System Description For an overview of the component/system, refer to: Fuel System Description

Component Description
K20 Engine Control Module The control module controls a series of actuators to ensure optimal engine performance. The control module does this by reading values from a variety of sensors, interprets the data and adjusts the engine actuators accordingly.
Q18A Fuel Pressure Regulator 1 The fuel pressure regulator is a solenoid valve that restricts the flow of fuel to the high pressure fuel pump and thereby controls the pressure the pump can produce.
Q18B Fuel Pressure Regulator 2 The fuel pressure regulator is the solenoid valve that controls the pressure in the fuel rail.

Conditions for Running the DTC P228A Engine = Running Fuel Rail Pressure is being controlled by Fuel Pressure Regulator 1 & 3. Ignition and Start Signal = Greater than 11 V Frequency the DTC runs = Continuously — After the running conditions are met P228B Engine = Running Fuel Rail Pressure is being controlled by Fuel Pressure Regulator 2. Ignition and Start Signal = Greater than 11 V Frequency the DTC runs = Continuously — After the running conditions are met Conditions for Setting the DTC Fuel Rail Pressure = Not within a calibrated range — For greater than 8 s Actions Taken When the DTC Sets DTCs listed in the DTC Descriptor category = Type A DTC Conditions for Clearing the DTC DTCs listed in the DTC Descriptor category = Type A DTC Reference Information Schematic Reference Engine Controls Schematics Connector End View Reference Master Electrical Component List Electrical Information Reference Circuit Testing Connector Repairs Testing for Intermittent Conditions and Poor Connections Wiring Repairs DTC Type Reference Powertrain Diagnostic Trouble Code (DTC) Type Definitions Scan Tool Reference Control Module References Circuit/System Verification

  1. Ignition » On / Vehicle » In Service Mode
  2. Verify there are no DTCs set related to the following component/system: Fuel System ⇒ If a related DTC is set Refer to: Diagnostic Trouble Code (DTC) List - Vehicle ⇓ If a related DTC is not set
  3. Verify the following conditions do not exist: Aftermarket equipment/accessories: Performance Components — Installed Fuel — Contamination Refer to: Fuel System Specifications or Contaminants-in-Fuel Diagnosis ⇒ If a condition exists Repair or replace as necessary ⇓ If no condition exists
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data. Verify the DTC does not set. ⇒ If the DTC sets Refer to: Circuit/System Testing ⇓ If the DTC is not set
  5. All OK. Circuit/System Testing
  6. Ignition/Vehicle » Off
  7. Verify the condition does not exist: Fuel System — Leaking Refer to: Fuel Leak Diagnosis ⇒ If the condition exists Repair or replace as necessary ⇓ If no condition exists
  8. Engine » Idling
  9. Verify the scan tool parameter: Fuel Pressure Sensor = 370 to 450 kPa (54 to 65 PSI) ⇒ If less than 370 kPa (54 PSI) Refer to: Fuel System Diagnosis ⇒ If greater than 450 kPa (65 PSI) Refer to: Fuel Return System Diagnosis ⇓ If between 370 and 450 kPa (54 and 65 PSI)
  10. Perform the following procedure/test: Cylinder Power Balance Test Verify the procedure/test passes. ⇒ If the procedure/test does not pass Replace the component that failed the test: Q17 Fuel Injector ⇓ If the procedure/test passes
  1. Perform the scan tool control function: Fuel Pressure Regulator » Increase & Decrease Verify the scan tool parameter: Fuel Rail Pressure Sensor = The value should change with each command. ⇒ If the value does not change Replace the component: Q18A Fuel Pressure Regulator 1 & Q18C Fuel Pressure Regulator 3 ⇓ If the value changes
  2. Perform the scan tool control function: Fuel Pressure Control - Regulator 2 » Increase & Decrease Verify the scan tool parameter: Fuel Rail Pressure Sensor = The value should change with each command. ⇒ If the value does not change Replace the component: Q18B Fuel Pressure Regulator 2 ⇓ If the value changes
  1. Perform the scan tool control function: Fuel Rail Pressure » Increase & Decrease Verify the following parameters are within 2,000 kPa (290 PSI) of each other: Desired Fuel Rail Pressure Fuel Rail Pressure ⇒ If not within 2,000 kPa (290 PSI) of each other Refer to: Fuel System Diagnosis - High Pressure Side ⇓ If within 2,000 kPa (290 PSI) of each other
  2. Test or replace the component: G18 Fuel Pump - High Pressure Repair Instructions Perform the Diagnostic Repair Verification after completing the repair: Diagnostic Repair Verification High Pressure Diesel Fuel Injection Rail Replacement — Q18B Fuel Pressure Regulator 2 High Pressure Diesel Fuel Injector Replacement High Pressure Diesel Fuel Pump Replacement — G18 Fuel Pump - High Pressure or Q18A  Fuel Pressure Regulator 1 & Q18C Fuel Pressure Regulator 3 For control module replacement, programming, and setup refer to: Control Module References