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Tahoe / Yukon Service Manual

DTC P2564, P2565, or U0656

Engine Controls and Fuel - 3.0L LM2 Diesel | Diagnostic Information and Procedures | Document ID: 5507640 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 P2564 Turbocharger/Supercharger Boost Control Position Sensor Circuit Low DTC P2565 Turbocharger/Supercharger Boost Control Position Sensor Circuit High DTC U0656 Lost Communication with Turbocharger/Supercharger Boost Control Position Sensor Diagnostic Fault Information

Circuit Short to Ground Open/High Resistance Short to Voltage Signal Performanc
5 V Reference P0641**, U0656** P2565*, U0656 P0641**, U0656** —
Serial Data U0656** U0656 U0656** —
Low Reference — P2564*, U0656 — —
* This DTC sets when there is an internal component issue: M103 Turbocharger Vane Position Actuator ** Additional DTCs may set

Typical Scan Tool Data Turbocharger/Supercharger Boost Control Position Sensor

Circuit Short to Ground Open Short to Voltage
Operating Conditions: Engine = Running Accessories = Off Parameter Normal Range: 3 to 4 V
5 V Reference 0.0 V 3.5 V 3.5 V
Circuit Short to Ground Open Short to Voltage
Serial Data 2.8 V 0.0 V 2.9 V
Low Reference — 0.0 V —

Circuit/System Description For an overview of the component/system, refer to: Compressor Air Intake Turbocharger System Description

Circuit Description
5 V Reference Regulated voltage supplied by the control module.
Serial Data The control module input circuit has an internal resistance connected to 5 V. Digitally encoded information for communication between devices.
Low Reference Grounded through the control module.
Component Description
K20 Engine Control Module The control module contains a microprocessor used to process input data to control outputs. 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.
M103 Turbocharger Vane Position Actuator The assembly has several functions: The valve is actuated by a 12 V DC motor. A spring is used to keep the valve in the open position. The valve actuator motor moves the valve in the closed direction. The more current flows through the motor, the more the valve closes. The component M103 contains a contactless inductive position sensor. A fixed transmitter coil excites a movable rotor, which in turn induces a current in a fixed receiver coil. The current varies with the angle of the rotor. Electronics inside the sensor convert the current into digital data which is transmitted via a serial data circuit to the control module K20.

Conditions for Running the DTC P2564, P2565 DTC U0656 = Not set Engine ≠ Cranking Ignition = On or Engine = Running Ignition Voltage = Greater than 11 V Frequency the DTC runs = Continuously — After the running conditions are met U0656 Ignition = On or Engine = Running Frequency the DTC runs = Continuously — After the running conditions are met Conditions for Setting the DTC P2564 Turbocharger/Supercharger Boost Control Position Sensor = Less than 0.3 V — For greater than 1  s P2565 Turbocharger/Supercharger Boost Control Position Sensor = Greater than 4.8 V — For greater than 1 s U0656 Serial Data circuit = Message Counter Incorrect /Too Many Pulses /Too Few Pulses — For greater than 1 s Actions Taken When the DTC Sets DTCs listed in the DTC Descriptor category = Type A DTC Reduced Engine Power = Active P16 Instrument Cluster = Reduced Engine Power Warning Message = Service Emission System /Service Exhaust Fluid System Conditions for Clearing the DTC DTCs listed in the DTC Descriptor category = Type A DTC Diagnostic Aids A high resistance condition on the component circuits may cause the DTC to set. A weak battery may cause this DTC to set. 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 DTC P0641, P0651, P0697, or P06A3 is not set. ⇒ If any of the DTCs are set Refer to: DTC P0641, P0651, P0697, or P06A3 ⇓ If none of the DTCs are set
  3. Verify DTC P2564, P2565, U0656 is not set. ⇒ If only DTC P2564, P2565 is set Replace the component: M103 Turbocharger Vane Position Actuator ⇒ If DTC U0656 and one or more of the DTCs P2564, P2565 is set Refer to: Circuit/System Testing ⇓ If none of the DTCs are set
  4. Perform the scan tool control function: Turbocharger/Supercharger Boost Control Position » Increase & Decrease Verify the scan tool parameter: Turbocharger/Supercharger Boost Control Position Sensor = Desired Turbocharger/Supercharger Boost Control Position ⇒ If not the specified state Refer to: Circuit/System Testing ⇓ If the specified state
  5. Verify the scan tool parameter: Turbocharger/Supercharger Boost Control Position Sensor = The value should not spike or drop out. Perform the action while monitoring the parameter: Wiggle the harness and connector: M103 Turbocharger Vane Position Actuator Wiggle the harness and connector: K20 Engine Control Module ⇒ If the value spikes or drops out Repair as necessary » Wiring / Terminal(s) / Electrical Connector(s) ⇓ If the value does not spike or drop out
  6. 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 does not set
  7. All OK. Circuit/System Testing
  1. Ignition/Vehicle & All vehicle systems » Off
  2. Disconnect the electrical connector: M103 Turbocharger Vane Position Actuator
  3. Test for less than 5 Ω between the test points: Low Reference circuit terminal 3 & Ground ⇒ If 5 Ω or greater 3.1. Disconnect the appropriate electrical connector: K20 Engine Control Module 3.2. Test for less than 2 Ω between the test points: Low Reference circuit terminal 3 @ Component harness & The other end of the circuit @ Control module harness ⇒ If 2 Ω or greater » Repair the open/high resistance in the circuit. ⇒ If less than 2 Ω » Replace the component: K20 Engine Control Module ⇓ If less than 5 Ω
  4. Ignition » On / Vehicle » In Service Mode
  5. Test for 4.8 to 5.2 V between the test points: 5 V Reference circuit terminal 4 & Low Reference circuit terminal 3 ⇒ If less than 4.8 V 5.1. Ignition/Vehicle » Off 5.2. Disconnect the appropriate electrical connector: K20 Engine Control Module 5.3. Test for infinite resistance between the test points: 5 V Reference circuit terminal 4 @ Component harness & Ground ⇒ If less than infinite resistance » Repair the short to ground on the circuit. ⇓ If infinite resistance 5.4. Test for less than 2 Ω between the test points: 5 V Reference circuit terminal 4 @ Component harness & The other end of the circuit @ Control module harness ⇒ If 2 Ω or greater » Repair the open/high resistance in the circuit. ⇒ If less than 2 Ω » Replace the component: K20 Engine Control Module ⇒ If greater than 5.2 V 5.1. Ignition/Vehicle » Off 5.2. Disconnect the appropriate electrical connector: K20 Engine Control Module 5.3. Ignition » On / Vehicle » In Service Mode 5.4. Test for less than 1 V between the test points: 5 V Reference circuit terminal 4 @ Component harness & Ground ⇒ If 1 V or greater » Repair the short to voltage on the circuit. ⇒ If less than 1 V » Replace the component: K20 Engine Control Module ⇓ If between 4.8 and 5.2 V
  6. Test for 4.8 to 5.2 V between the test points: Serial Data circuit terminal 2 @ Component harness & Ground ⇒ If less than 4.8 V 6.1. Ignition/Vehicle » Off 6.2. Disconnect the appropriate electrical connector: K20 Engine Control Module 6.3. Test for infinite resistance between the test points: Serial Data circuit terminal 2 @ Component harness & Ground ⇒ If less than infinite resistance » Repair the short to ground on the circuit. ⇓ If infinite resistance 6.4. Test for infinite resistance between the test points: Serial Data circuit terminal 2 @ Component harness & Low Reference circuit terminal 3 @ Component harness ⇒ If less than infinite resistance » Repair the short between the circuits. ⇓ If infinite resistance 6.5. Test for less than 2 Ω between the test points: Serial Data circuit terminal 2 @ Component harness & The other end of the circuit @ Control module harness ⇒ If 2 Ω or greater » Repair the open/high resistance in the circuit. ⇒ If less than 2 Ω » Replace the component: K20 Engine Control Module ⇒ If greater than 5.2 V 6.1. Ignition/Vehicle » Off 6.2. Disconnect the appropriate electrical connector: K20 Engine Control Module 6.3. Ignition » On / Vehicle » In Service Mode 6.4. Test for less than 1 V between the test points: Serial Data circuit terminal 2 @ Component harness & Ground ⇒ If 1 V or greater » Repair the short to voltage on the circuit. ⇓ If less than 1 V » Replace the component: K20 Engine Control Module ⇓ If between 4.8 and 5.2 V
  7. Test or replace the component: M103 Turbocharger Vane Position Actuator Repair Instructions Perform the Diagnostic Repair Verification after completing the repair: Diagnostic Repair Verification Variable Geometry Turbocharger Actuator Replacement — M103 Turbocharger Vane Position Actuator For control module replacement, programming, and setup refer to: Control Module References Additional Procedures Barometric Pressure Sensor Reset — Perform only when the following component/system is replaced or serviced: K20 Engine Control Module Turbocharger/Supercharger Boost Control Initial Position Learn — Perform only when the following component/system is replaced or serviced: – K20 Engine Control Module — Programmed / Replaced – Turbocharger — Cleaned / Replaced
  1. Ignition » On / Vehicle » In Service Mode
  2. Verify that all scan tool Event Data parameters under the following data list displays No: Exhaust Gas Recirculation System Malfunction Warning Event Data ⇒ If not the specified state Operate the vehicle within the Conditions for Running the DTC for the DTC identified by the Event Data parameter displaying Yes. ⇓ If the specified state
  3. All OK.