GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2007 🢒 TopKick C-Series (Conventional) C4/C5 🢒 DTC 🢒 DTC P2008

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 signal circuit. The ECM supplies voltage to the VNT control solenoid on the signal 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 an excessively low signal current, this DTC will set.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P2008 Turbocharger Vane Position Control Solenoid Valve Circuit Low Current

Conditions for Running the DTC
    • The ignition is ON.
    • The battery voltage is between 10-16 volts.
    • The VNT final duty is between 10-90 percent.

Conditions for Setting the DTC

The VNT control solenoid valve circuit is less than 0.1 volt.

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 the VNT control solenoid valve control.
    • The ECM closes the exhaust gas recirculation (EGR) valve and holds the EGR control.
    • The ECM inhibits cruise control.

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
       - Rubbed through wire insulation
       - Broken wire inside the insulation
    • 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 cannot duplicate the DTC, using the information included in the Failure Records can help to locate an intermittent condition.

Step

Action

Values

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. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Perform the actuator test for EGR Solenoid Control with a scan tool.
  4. Inspect the EGR position.

Was a condition found?

--

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 7

3

  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 4

Go to Diagnostic Aids

4
  1. Turn OFF the ignition.
  2. Disconnect the variable nozzle turbocharger (VNT) solenoid and the engine control module (ECM).
  3. Inspect for an intermittent and for a poor connections at the harness connector of the VNT solenoid and the ECM.
  4. Repair the connections, as necessary.

Did you find and correct the condition?

--

Go to Step 11

Go to Step 5

5
  1. Test the 12-volt feed circuit between the VNT solenoid valve and the in-line connector for the following conditions:
    2. • An open circuit
    • A short to ground circuit
  2. Repair the circuits, as necessary.

Did you find and correct the condition?

--

Go to Step 11

Go to Step 6

6
  1. Test the signal circuit between the ECM and the VNT control solenoid valve for the following conditions:
    2. • An open circuit
    • A short to ground circuit
  2. Repair the circuits, as necessary.

Did you find and correct the condition?

--

Go to Step 11

Go to Step 7

7

  1. Turn OFF the ignition.
  2. Disconnect the VNT control solenoid valve connector.
  3. Inspect for an intermittent and for a poor connection at the harness connector of the VNT control solenoid valve.

Did you find and correct the condition?

--

Go to Step 11

Go to Step 8

8
  1. Turn OFF the ignition.
  2. Disconnect the VNT control solenoid valve connector.
  3. Measure the resistance at the VNT control solenoid valve.

Is the resistance at the specified value?

3.4-4.1ohms at 25°C (77°F)

Go to Step 10

Go to Step 9

9

Replace the vane position control solenoid valve. Refer to Turbocharger Control Solenoid Valve Replacement .

Did you complete the replacement?

--

Go to Step 11

--

10

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 11

--

11
  1. Clear the DTCs with a scan tool.
  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 2

Go to Step 12

12

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