P2261

DTC P2261

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions)provides an overview of each diagnostic category.

DTC Descriptor
DTC P2261
- Turbocharger Bypass Valve Stuck Closed

System Description

The Borg-Warner(TM) dual-scroll turbocharger incorporates a wastegate that is controlled by a pressure differential, that is determined by the engine control module (ECM) by means of a PWM solenoid, in order to regulate the pressure ratio of the compressor. A bypass valve is integrated within the unit, and is also controlled by the ECM by utilizing a remotely mounted solenoid to prevent compressor surging and damage from vibrations by opening during abrupt closed throttle conditions. When the valve is commanded open during closed throttle deceleration conditions, the bypass valve allows the air to recirculate in the turbocharger and maintain compressor speed. Within a calibrated range during the closed throttle event, or upon a wide open throttle command, the valve will then close to optimize turbocharger response.

Front wheel drive platforms also incorporate a bypass valve vacuum tank. The purpose of the tank is to provide an instant source of vacuum to the bypass valve, when it is commanded open by the ECM. This results in less pressure buildup under closed throttle conditions, thereby reducing compressor noise and surge.

The purpose of this diagnostic is to determine if the bypass valve is stuck closed. The ECM will first verify the integrity of the following sensors. The ECM then compares the actual measured mass air flow (MAF) to a modeled airflow that is derived from these inputs:

* Throttle position
* Engine speed
* Intake air pressure sensor
* Manifold absolute pressure (MAP) sensor

Conditions for Running the DTC

* DTC P0033, P0034, P0035, P0101, P0102, P0103, P0236, P0237, or P0238 is not set.
* The boost pressure versus the BARO pressure ratio is between1.1-3.3.
* The turbocharger bypass valve has been commanded Open greater than 6% for greater than 1 s immediately after an abrupt closed throttle has occurred and the resulting pressure ratio across the compressor exceeds the calibrated pressure ratio limit.
* The DTC runs continuously when the above conditions have ben met.

Conditions for Setting the DTC

The ECM has detected a series of pulsations in the induction system that exceed a calibrated threshold.

Action Taken When the DTC Sets

DTC P2261 is a Type B DTC.

Conditions for Clearing the MIL/DTC

DTC P2261 is a Type B DTC.

Reference Information
Schematic Reference

Engine Controls Schematics ([1][2]Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector End Views By Name)
Description and Operation

Turbocharger System Description (Description and Operation)
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Powertrain Diagnostic Trouble Code (DTC) Type Definitions)
Scan Tool Reference

Control Module References (Programming and Relearning)for scan tool information.

Circuit/System Verification

1. Ignition ON, command the Turbocharger Bypass Solenoid Valve ON and OFF with a scan tool. A click should be heard and felt in response to the commands.
2. Set up the scan tool for a snapshot of the induction data list. With the emergency brake on, the vehicle transmission in neutral, and the engine idling, perform a wide open throttle and then quickly release the accelerator. Review the Boost Pressure Sensor parameter. There should not be any abnormal pulsations of the parameter.
3. With the parking brake ON and the engine idling in neutral, perform an audible test of the valve by depressing the throttle wide open, then quickly releasing it to a closed throttle position. A valve that is stuck shut will generate a rapid pulsating sound. There should not be any unusual noise.
4. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing

1. Verify the integrity of the turbocharger bypass solenoid valve system by inspecting for any the following conditions:

* Vacuum leaks
* Vacuum line restrictions
* Damaged components
* Improper routing or connecting of the vacuum hoses on the turbocharger bypass valve solenoid, the bypass valve, and the bypass valve vacuum tank

• If a condition is found, repair or replace the affected component as necessary.

2. If all inspections are normal, test or replace the Q40 Turbocharger Bypass Solenoid Valve.

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Control Module References (Programming and Relearning)for ECM replacement, setup, and programming
* Charge Air Bypass Valve Replacement (Service and Repair)for turbocharger bypass solenoid valve replacement