For 1990-2009 cars

### Circuit Description

Supercharger boost pressure is regulated to prevent engine and drive train damage. When the engine is operating under high boost conditions, the powertrain control module (PCM) limits boost pressure to 12 psi or less. The PCM disables boost under the following conditions:

• | When reverse gear is selected

• | When the vehicle is decelerating

• | If an intercooler pump failure is detected

• | If the intake air temperature (IAT) sensor 2 becomes excessively high

• | If the engine coolant temperature (ECT) becomes excessively high

• | Under heavy load in first and second gear at engine speeds above 5,800 RPM

• | When drivetrain abuse is detected

The PCM controls boost pressure by pulse width modulation (PWM) of the boost control solenoid. The boost control solenoid is a normally open valve. Under most conditions, the PCM commands the boost control solenoid to operate at a 99-100 percent duty cycle. This keeps the solenoid valve closed and allows only inlet vacuum from the supercharger plenum to the bypass valve actuator to control the position of the bypass valve. At idle, engine vacuum is applied to the upper side of the bypass valve actuator, counteracting spring tension to hold the bypass valve open. When the engine load is increased, the engine vacuum is decreased, causing the spring in the bypass valve to overcome the diminishing applied vacuum, closing the bypass valve and allowing the boost pressure to increase. When reduced boost pressure is desired, the PCM commands the boost control solenoid to operate at a 0-98 percent duty cycle. This opens the solenoid valve and allows boost pressure to enter the bypass valve actuator at the lower side to counteract the spring tension, opening the bypass valve and recirculating excess boost pressure back into the supercharger inlet.

The PCM monitors the voltage level on the boost control solenoid control circuit. If the PCM detects an improper voltage level on the supercharger boost control solenoid control circuit, DTC P0033 sets.

### DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0033 Supercharger Bypass Valve Solenoid Control Circuit

### Conditions for Running the DTC

• | The ignition is ON.

| OR

• | The engine is running.

• | The ignition 1 voltage is between 11-18 volts.

• | This DTC runs continuously within the enabling conditions.

### Conditions for Setting the DTC

The PCM detects an improper voltage level on the boost control solenoid control circuit for more than 20 seconds.

### Action Taken When the DTC Sets

• | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.

• | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

### Conditions for Clearing the MIL/DTC

• | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.

• | A current DTC, Last Test Failed, clears when the diagnostic runs and passes.

• | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.

• | Clear the MIL and the DTC with a scan tool.

### Diagnostic Aids

• | For additional information, review the Boost Control System Description. Refer to Boost Control System Description .

• | If the condition is intermittent, refer to Inducing Intermittent Fault Conditions and Intermittent Conditions .

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End Views or Powertrain Control Module Connector End Views
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 |

1. Turn ON the ignition, with the engine OFF.
2. Select Boost Solenoid in the Engine Output Controls on the scan tool.
3. Command the Boost Solenoid Duty Cycle from 0 percent to 10 percent with the scan tool.

When the solenoid is commanded ON, do you hear a series of clicks?

--

Go to Step 3

Go to Step 4

3 |

1. Observe the Freeze Frame/Failure Records for this DTC.
2. Turn OFF the ignition for 90 seconds.

Important: Some failure modes of this diagnostic only run at Ignition ON.

3. Turn ON the ignition for 90 seconds.
4. Start the engine.
5. 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.

Did the DTC fail this ignition cycle?

--

Go to Step 4

Go to Diagnostic Aids

4 | Inspect the fuse in the ignition 1 voltage circuit of the boost control solenoid. Is the fuse open? | -- | Go to Step 5 | Go to Step 7
5 | Test for shorted terminals and for an improper connection at the boost control solenoid. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs. Did you find and correct the condition? | -- | Go to Step 20 | Go to Step 6
6 |

1. Connect a DMM to the terminals of the boost control solenoid.
2. Measure the resistance of the boost control solenoid. Refer to Circuit Testing.

Is the resistance within the specified range?

20-35 ohms

Go to Step 16

Go to Step 18

7 | Test for an intermittent and for a poor connection at the boost control solenoid. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs. Did you find and correct the condition? | -- | Go to Step 20 | Go to Step 8
8 |

1. Connect a DMM to the terminals of the boost control solenoid.
2. Measure the resistance of the boost control solenoid. Refer to Circuit Testing.

Is the resistance within the specified range?

20-35 ohms

Go to Step 9

Go to Step 18

9 |

1. Turn ON the ignition, with the engine OFF.
2. Measure the battery voltage with a DMM. Refer to Measuring Voltage.
3. Connect a test lamp between the ignition 1 voltage circuit of the boost control solenoid and a good ground. Refer to Troubleshooting with a Test Lamp and Probing Electrical Connectors.
4. Connect the DMM to the probe of the test lamp and a good ground. Refer to Measuring Voltage Drop and Troubleshooting with a Digital Multimeter.

Is the voltage within 1 volt of the specified value?

B+

Go to Step 10

Go to Step 17

10 |

1. Connect a test lamp between the control terminal and the ignition 1 voltage terminal of the boost control solenoid harness connector. Refer to Troubleshooting with a Test Lamp and Probing Electrical Connectors.
2. Select Boost Solenoid in the Engine Output Controls on the scan tool.
3. Command the Boost Solenoid Duty Cycle from 0 percent to 10 percent several times with the scan tool.

Does the test lamp turn ON and OFF with each command?

--

Go to Diagnostic Aids

Go to Step 11

11 | Does the test lamp remain illuminated? | -- | Go to Step 12 | Go to Step 13
12 | Test for shorted terminals and for an improper connection at the powertrain control module (PCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs. Did you find and correct a condition? | -- | Go to Step 20 | Go to Step 15
13 | Test for an intermittent and for a poor connection at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs. Did you find and correct a condition? | -- | Go to Step 20 | Go to Step 14
14 | Test the boost control solenoid control circuit for the following conditions:

• | A high resistance

• | An open circuit

• | A short to voltage

Refer to Circuit Testing and Wiring Repairs.

Did you find and correct the condition?

--

Go to Step 20

Go to Step 19

15 | Test the boost control solenoid control circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs. Did you find and correct the condition? | -- | Go to Step 20 | Go to Step 19
16 | Repair the short to ground in the boost control solenoid ignition 1 voltage circuit. Refer to Wiring Repairs. Did you complete the repair? | -- | Go to Step 20 | --
17 | Repair the high resistance or an open in the boost control solenoid ignition 1 voltage circuit. Refer to Wiring Repairs. Did you complete the repair? | -- | Go to Step 20 | --
18 | Replace the boost control solenoid. Refer to Boost Control Solenoid Replacement . Did you complete the replacement? | -- | Go to Step 20 | --
19 | Replace the PCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 20 | --
20 |

1. Clear the DTC with a scan tool.
2. Turn OFF the ignition for 90 seconds.
3. Start the engine.
4. 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.

Did the DTC fail this ignition?

--

Go to Step 2

Go to Step 21

21 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | Go to Diagnostic Trouble Code (DTC) List - Vehicle | System OK