GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The position of the turbocharger vanes is controlled by the engine control module (ECM). The ECM utilizes a turbocharger vane control solenoid valve and a turbocharger vane position sensor to control the turbocharger vanes. When the engine is not under load, the turbocharger vanes are in an open position, or no boost condition. When the engine is under load, the ECM commands the control solenoid valve to close the turbocharger vanes, thus increasing the boost. The ECM will vary the boost dependant upon the load requirements of the engine. The vane position sensor uses the following three circuits:

    • A 5-volt reference circuit
    • A low reference circuit
    • A signal circuit

The ECM provides the sensor with 5 volts on the 5-volt reference circuit and a ground on the low reference circuit. Movement of the sensor from the closed position to the open position provides the ECM with a signal voltage through the position sensor signal circuit. If the ECM detects an excessively low position sensor signal voltage, DTC P2564 will set.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P2564 Turbocharger Vane Control Position Sensor Circuit Low Voltage

Conditions for Running the DTC

    • The engine is running.
    • DTC P2564 runs continuously once the above conditions have been met.

Conditions for Setting the DTC

    • The turbocharger vane position sensor voltage is less than 1 volt.
    • The above condition exists for more than 6 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.

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Engine Control Module Connector End Views or Engine Controls 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. Monitor the DTC Information with a scan tool.

Is DTC P0652 also set?

--

Go to DTC P0652

Go to Step 3

3

  1. Start the engine.
  2. Select the TC Vane Position Sensor test in Scan Tool Output Controls.
  3. With the engine at idle, observe the turbocharger (TC) vane position and the desired TC vane position while commanding the TC vane position sensor to 100 percent with the scan tool.

Is the TC vane position at or near the desired TC vane position while commanding the TC vane position sensor from 0-100 percent?

--

Go to Step 4

Go to Step 5

4

  1. Observe the Freeze Frame/Failure Records for this DTC.
  2. Turn OFF the ignition for 30 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 5

Go to Intermittent Conditions

5

  1. Turn OFF the ignition.
  2. Disconnect the turbocharger vane position sensor.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage from the 5-volt reference circuit to a good ground with a DMM.

Is the voltage less than the specified value?

4.8 V

Go to Step 7

Go to Step 6

6

Measure the voltage from the signal circuit to a good ground with a DMM.

Is the voltage less than the specified value?

4.8 V

Go to Step 8

Go to Step 9

7

  1. Turn OFF the ignition.
  2. Disconnect the engine control module (ECM).
  3. Test the vane position sensor 5-volt reference circuit for an open and for a high resistance. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 13

Go to Step 10

8

  1. Turn OFF the ignition.
  2. Disconnect the ECM.
  3. Test the vane position sensor signal circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 13

Go to Step 10

9

Test for an intermittent and for a poor connection at the vane position sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

--

Go to Step 13

Go to Step 11

10

Test for an intermittent and for a poor connection at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

--

Go to Step 13

Go to Step 12

11

Replace the turbocharger vane position sensor. Refer to Turbocharger Vane Position Sensor Replacement .

Did you complete the replacement?

--

Go to Step 13

--

12

Replace the ECM. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 13

--

13

  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Perform the turbocharger learn procedure. Refer to Turbocharger Learn .
  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?

--

Go to Step 2

Go to Step 14

14

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