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Tahoe / Yukon Service Manual

DTC P1255

Engine Controls and Fuel - 3.0L LM2 Diesel | Diagnostic Information and Procedures | Document ID: 5501056 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 P1255 Fuel Pump Power Control Module Driver Temperature Too High Circuit/System Description For an overview of the component/system, refer to: Fuel System Description

Component Description
K111 Fuel Pump Power Control Module The control module contains a microprocessor used to process input data to control outputs. The control module communicates with the engine control module via serial data.

When the ignition is turned On, the ECM sends a 12 V signal to the control module K111 to enable the fuel pump. If the engine is not started, the control module K111 turns the fuel pump Off after 6 s. Conditions for Running the DTC Engine = Cranking or Running Fuel Pump Command = On Ignition and Start Signal = Greater than 9 V Frequency the DTC runs = Continuously — After the running conditions are met Conditions for Setting the DTC K111 Fuel Pump Power Control Module = Warmer than 160°C (320°F) — For greater than 1 s Actions Taken When the DTC Sets DTCs listed in the DTC Descriptor category = Type B DTC Conditions for Clearing the DTC DTCs listed in the DTC Descriptor category = Type B 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 DTC U18A2 is not set. ⇒ If the DTC is set Refer to: Diagnostic Trouble Code (DTC) List - Vehicle ⇓ If the DTC is not set
  3. Verify the component location is free of debris, clutter or any obstruction that may reduce airflow which could cause an overheat condition: K111 Fuel Pump Power Control Module ⇒ If a condition exists 3.1. Repair as necessary 3.2. Perform the following action: Clear the DTCs. 3.3. Test drive the vehicle. 3.4. Verify DTC P1255 is not set. ⇒ If the DTC sets » Replace the component: K111 Fuel Pump Power Control Module ⇓ If the DTC is not set 3.5. All OK. ⇓ If no condition exists
  4. Perform the following action: Clear the DTCs.
  5. Test drive the vehicle.
  6. Verify DTC P1255 is not set. ⇒ If the DTC is set Replace the component: K111 Fuel Pump Power Control Module ⇓ If the DTC is not set
  7. All OK. Repair Instructions Perform the Diagnostic Repair Verification after completing the repair: Diagnostic Repair Verification For control module replacement, programming, and setup refer to: Control Module References