For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category.

### DTC Descriptors

DTC P0033 : Turbocharger Bypass Solenoid Valve Control Circuit
DTC P0034: Turbocharger Bypass Solenoid Valve Control Circuit Low Voltage
DTC P0035: Turbocharger Bypass Solenoid Valve Control Circuit High Voltage

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Ignition Voltage | P0033, P0034 | P0033 | -- | --
Turbocharger Bypass Solenoid Valve Control Circuit | P0034 | P0033 | P0035 | --

### Circuit/System Description

The turbocharger bypass solenoid valve is used to prevent the compressor from exceeding the pump limit at low compressor flow and high pressure. This occurs when the engine is running with a load and the throttle suddenly closes. In this case, flow is almost null and pressure is very high. This not only is damaging to the turbocharger, but also generates noise and decelerates turbine speed. The bypass solenoid valve is pulse width modulated (PWM). Ignition voltage is supplied directly to the bypass solenoid valve. The engine control module (ECM) controls the solenoid valve by grounding the control circuit with a solid state device called a driver. The driver is equipped with a feedback circuit that is pulled-up to a voltage. The ECM can determine if the control circuit is open, shorted to ground, or shorted to a voltage by monitoring the feedback voltage.

### Conditions for Running the DTC

• | The engine speed is greater than 80 RPM.

• | The ignition voltage is between 10-18 volts.

• | The ECM has commanded the bypass solenoid valve ON and OFF at least once during the ignition cycle.

• | The DTCs run continuously once the above conditions are met.

### Conditions for Setting the DTC

#### P0033

The ECM detects the bypass solenoid valve control circuit is open. The condition exists for 4 seconds or a cumulative of 30 seconds.

#### P0034

The ECM detects the bypass solenoid valve control circuit is shorted to ground. The condition exists for 4 seconds or a cumulative of 30 seconds.

#### P0035

The ECM detects the bypass solenoid valve control circuit is shorted to voltage. The condition exists for 4 seconds or a cumulative of 30 seconds.

### Action Taken When the DTC Sets

DTC P0033, P0034, and P0035 are Type B DTCs.

### Conditions for Clearing the DTC

DTC P0033, P0034, and P0035 are Type B DTCs.

### Diagnostic Aids

If the condition is intermittent, move the related harnesses and connectors, with the engine operating, while monitoring the circuit status for the component with a scan tool. The circuit status parameter changes from OK or Not Ran to Fault if there is a condition with the circuit or a connection.

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Turbocharger System Description

#### 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 for scan tool information

### Circuit/System Verification

1. Ignition ON, command the Turbocharger Bypass Solenoid Valve between Boost and Bypass with a scan tool. You should hear an audible click.
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. Ignition OFF, disconnect the harness connector at the Q40 turbocharger bypass solenoid valve.
2. 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. If the circuit tests normal and the ignition voltage circuit fuse is open, test all components connected to the ignition voltage circuit and replace as necessary.

3. Connect a test lamp between the control circuit terminal 1 and the ignition circuit terminal 2.

Note: The control circuit for the turbocharger bypass solenoid valve is pulled-up to voltage within the ECM, 2.6-4.6 V on the control circuit is normal.

4. Command the Turbocharger Bypass Solenoid Valve between Boost and Bypass then select exit with a scan tool. The test lamp should illuminate and then go OFF.

⇒ | If the test lamp is always ON, test the control circuit terminal 2 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 terminal 2 for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K20 ECM.

5. Test for 2.6-4.6 V between the control circuit terminal 2 and ground.

⇒ | If the voltage is not within the specified range, replace the K20 ECM.

6. If all circuits test normal, test or replace the Q40 turbocharger bypass solenoid valve.

### Component Testing

1. Ignition OFF, disconnect the harness connector at the Q40 turbocharger bypass solenoid valve.
2. Test for 15-20 Ω between the control terminal 2 and the ignition terminal 1 of the Q40 turbocharger bypass solenoid valve.

⇒ | If not within the specified range, replace the Q40 turbocharger bypass solenoid valve.

3. Test for infinite resistance between each terminal and the Q40 turbocharger bypass solenoid valve housing.

⇒ | If not the specified value, replace the Q40 turbocharger bypass solenoid valve.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Turbocharger Disassemble

• | Control Module References for engine control module replacement, setup, and programming