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Home >> Chevrolet >> 2010 >> Cobalt L4-2.0L Turbo >> Repair and Diagnosis >> A L L Diagnostic Trouble Codes ( DTC ) >> Testing and Inspection >> P Code Charts >> P0034

P0034




DTC P0033-P0035

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 Descriptors
DTC P0033
- Turbocharger Bypass Valve Solenoid Control Circuit

DTC P0034
- Turbocharger Bypass Valve Solenoid Control Circuit Low Voltage

DTC P0035
- Turbocharger Bypass Valve Solenoid Control Circuit High Voltage

Diagnostic Fault Information





Circuit/System Description

The BorgWarner(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 compressor bypass valve also controlled by the ECM by utilizing a remotely mounted solenoid is integrated into the unit to prevent compressor surging and damage from vibrations by opening during abrupt closed throttle conditions. When the valve is 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 turbo response. The bypass valve solenoid has the following circuits:

* Ignition voltage
* Turbocharger bypass valve solenoid control

As engine load and RPM increases the Turbocharger Bypass Solenoid parameter should remain commanded ON by the ECM. As soon as the throttle closes the Turbocharger Bypass Solenoid parameter should be commanded OFF by the ECM, in order to allow the turbocharger bypass valve to open and allow the turbocharger air to recirculate, thereby preventing compressor surging.

Conditions for Running the DTCs

* The engine speed is greater than 80 RPM.
* The battery voltage is between 10-18 V.
* The bypass valve must be activated in order to set the open and short to ground faults.
* This DTC runs continuously within the enabling conditions.

Conditions for Setting the DTCs

The ECM detects an open, a short to ground, or a short to voltage on the turbocharger bypass valve solenoid control circuit for greater than 4 s continuously, or 50 s cumulative.

Action Taken When the DTCs Set

DTCs P0033, P0034, P0035 are Type B DTCs.

Conditions for Clearing the MIL/DTCs

DTCs P0033, P0034, P0035 are Type B DTCs.

Reference Information
Schematic Reference

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

Component Connector End Views (Connector Views)
Description and Operation

* Turbocharger System Description (Description and Operation)
* Boost Control 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. Use the scan tool output controls to command the Turbocharger Bypass Solenoid Command parameter ON and OFF. An audible click should be heard and felt.
2. 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. Clear the DTCs with a scan tool.
2. Ignition OFF, disconnect the harness connector at the Q40 bypass valve solenoid.
3. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal 2 and ground.

• If the test lamp does not illuminate test the ignition circuit for a short to ground or an open/high resistance.

4. Verify that a test lamp does not illuminate between the control circuit terminal 1 and ground.

• If the test lamp illuminates, test the control circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.

5. Connect a test lamp between the control circuit terminal 1 and the ignition circuit terminal 2.
6. Command the bypass solenoid ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

• If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the K20 ECM.
• If the test lamp is always OFF, test the control circuit for an open/high resistance. If the circuit tests normal, replace the K20 ECM.

7. If the circuits test normal, test or replace the Q40 charge air bypass valve solenoid.

Repair Instructions

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

* Charge Air Bypass Valve Solenoid Replacement (Charge Air Bypass Valve Solenoid Replacement)
* Control Module References (Programming and Relearning) for ECM replacement, setup, and programming

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