GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The variable nozzle turbocharger (VNT) control solenoid valve is located in the turbocharger. The VNT control solenoid valve is controlled by the engine control module (ECM). The VNT control solenoid valve has a 12-volt reference circuit and a VNT control circuit. The ECM supplies voltage to the VNT control solenoid on the 12-volt reference circuit. The VNT control solenoid valve is controlled by the time of voltage supply from the ECM to the VNT control solenoid valve. When the time of voltage supply increases, the VNT control solenoid valve position decreases. If the ECM detects a VNT position stuck, this DTC will set.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P2900 Turbocharger Vane Position Stuck

Conditions for Running the DTC

    • The engine is running 1100-2400 RPM.
    • The battery voltage is between 10-16 volts.
    • The VNT duty cycle is between 0-10 percent.
    • DTC P2007, P2008, P2564, or P2565 is not set.
    • ECT is between 78-88°C.

Conditions for Setting the DTC

    • The deviation of the actual VNT position and the desired VNT position is more than the threshold.
    • The fluctuation of the actual VNT position is less than the threshold.

Action Taken When the DTC Sets

    • The ECM illuminates the malfunction indicator lamp (MIL) and reduced engine power indicator lamp, if fitted, when the diagnostic runs and fails.
    • The ECM records the operating conditions at the time the diagnostic fails. The ECM stores this information in the Failure Records.
    • The ECM limits fuel injection quantity for fail-safe operation.
    • The ECM limits fuel rail pressure for fail-safe operation.
    • The ECM inhibits the cruise control.
    • The ECM closes the exhaust gas recirculation (EGR) valve and stops the EGR control.
    • The ECM limits the VNT control solenoid operation.

Condition for Clearing the DTC

    • A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
    • Clear the MIL and the DTC with a scan tool.

Diagnostic Aids

    • If an intermittent condition is suspected, the following may cause an intermittent:
       - Poor connections
       - A misrouted harness
    • Inspect for the following conditions:
       - Poor connection at ECM--Inspect the harness connectors for the following conditions:
   • Backed-out terminals
   • Improper mating
   • Broken locks
   • Improperly formed or damaged terminals
   • Poor terminal to wire connection
       - Damaged harness--Inspect the wiring harness for damage. If the harness appears to be OK, observe the Current VNT Position display on the scan tool while moving the connectors and the wiring harness related to the sensor. A change in the display will indicate the location of the fault.

Test Description

The number below refers to the step number on the diagnostic table.

  1. Operate the vehicle within the same conditions as when the DTC failed. If you can not duplicate the DTC, using the information included in the Failure Records can help to locate an intermittent condition.

  2. To perform the actuator test, the following condition must be met:

  3. • The engine speed is between 500-1,000 RPM.
    • The ECT is more than 70°C (32°F).
    • The PTO is OFF.
    • The transmission is in Park or Neutral.
  4. To perform the actuator test, the following condition must be met:

  5. • The engine speed is between 500-1,000 RPM.
    • The ECT is more than 70°C (32°F).
    • The PTO is OFF.
    • The transmission is in Park or Neutral.

Step

Action

Value

Yes

No

Schematic Reference: Engine Controls Schematics

1

Did you perform the Diagnostic System Check - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Turn OFF ignition for 30 seconds.
  2. Start the engine.
  3. Monitor the DTC information with a scan tool.

Is DTC P2007, P2008, P2564 or P2565 also set?

--

Go to Diagnostic Trouble Code (DTC) List - Vehicle

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Disconnect the variable nozzle turbocharger (VNT) position sensor.
  3. Inspect for an intermittent and for a poor connection at the harness connector of the VNT position sensor.

Did you find and correct the condition?

--

Go to Step 5

Go to Step 4

4

  1. Turn OFF the ignition for 30 seconds.
  2. Start the engine.
  3. 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. Observe the TC vane position.
  2. Connect the scan tool.
  3. Turn ON the ignition.
  4. Perform the actuator test for the TC vane position sensor with the scan tool.
  5. Observe the TC vane position.

Does the TC vane position operate through the entire specified range?

0-100 %

Go to Step 6

Go to Step 14

6

  1. Test the signal circuit between the engine control module (ECM) and the VNT position sensor for a short to voltage circuit.
  2. Repair the circuits, as necessary.

Did you find and correct the condition?

--

Go to Step 7

Go to Step 8

7

  1. Connect the VNT position sensor connector.
  2. Observe the Failure Records for this DTC.
  3. Turn OFF the ignition for 30 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?

--

Go to Step 8

Go to Step 9

8

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

Did you complete the replacement?

--

Go to Step 9

--

9

  1. Reconnect all previously disconnected harness connectors.
  2. Clear the DTCs with a scan tool.
  3. Turn OFF the ignition for 30 seconds.
  4. Start the engine.
  5. Operate the vehicle within the condition for running the DTC. You may also operate the vehicle within the condition that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

--

Go to Step 10

Go to Step 15

10

  1. Observe the TC vane position.
  2. Connect the scan tool.
  3. Turn ON the ignition.
  4. Perform the actuator test for the TC vane position.
  5. Observe the TC vane position.

Does the TC vane position operate through the entire specified range?

0-100%

Go to Step 11

Go to Step 12

11

Replace the turbocharger. Refer to Turbocharger Replacement .

Did you complete the replacement?

--

Go to Step 12

--

12

  1. Reconnect all previously disconnected harness connectors.
  2. Clear the DTCs with a scan tool.
  3. Turn OFF the ignition for 30 seconds.
  4. Start the engine.
  5. Operate the vehicle within the Conditions for Running the DTC. you may also operate the vehicle within the condition that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

--

Go to Step 13

Go to Step 15

13

Important: The new ECM must be programmed.

Replace the ECM. Refer to Engine Control Module Programming and Setup , Engine Control Module Replacement/Restore Fuel Rate Data , and Fuel Injector Flow Rate Programming .

Did you complete the replacement?

--

Go to Step 14

--

14

  1. Reconnect all previously disconnected harness connectors.
  2. Clear the DTCs with a scan tool.
  3. Turn OFF the ignition for 30 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?

--

Go to Step 2

Go to Step 15

15

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