GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2004 🢒 TopKick C-Series (Conventional) C4/C5 🢒 DTC 🢒 DTC P0046

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 control solenoid valve uses 2 circuits, a control circuit and a low reference circuit. The ECM uses a pulse width modulation (PWM) on the control circuit to control the solenoid valve. The ECM provides a ground on the low reference circuit. If the ECM detects that the commanded position of the turbocharger vanes does not match the actual position, DTC P0046 will set.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0046 Turbocharger Vane Control Position Performance

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

The ECM detects that the commanded position of the turbocharger vanes does not match the actual position.

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
    • If any service has been performed on the turbocharger or on the turbocharger components, a turbocharger relearn must be performed. Failure to perform the turbocharger learn procedure may cause this DTC to set. Refer to Turbocharger Learn .
    • For an intermittent condition, refer to Intermittent Conditions .

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 - Engine Controls?

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Go to Step 2

Go to Diagnostic System Check - Engine Controls

2
  1. Turn ON the ignition, with the engine OFF.
  2. Monitor the Diagnostic Trouble Code (DTC) Information with a scan tool.

Is DTC P0652, P0653, P2563, P2564, or P2565 also set?

--

Go to Diagnostic Trouble Code (DTC) List

Go to Step 3

3
  1. Perform the Turbocharger Learn Procedure. Refer to Turbocharger Learn .
  2. Turn OFF the ignition for 30 seconds.
  3. Turn ON the ignition, with the engine OFF.
  4. Clear the DTCs with the scan tool.

Is the procedure complete?

--

Go to Step 4

--

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 Diagnostic Aids

5
  1. Turn OFF the ignition for 30 seconds.
  2. Disconnect the turbocharger vane position sensor.
  3. 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 in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 6

6
  1. Disconnect the engine control module (ECM).
  2. Test for an intermittent and for a poor connection at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 7

7

Measure the resistance of the 5-volt reference circuit between the vane position sensor and the ECM, with a DMM.

Is the resistance more than the specified value?

5 ohms

Go to Step 16

Go to Step 8

8

Measure the resistance of the signal circuit between the vane position sensor and the ECM, with a DMM.

Is the resistance more than the specified value?

5 ohms

Go to Step 16

Go to Step 9

9
  1. Connect the vane position sensor.
  2. Disconnect the turbocharger vane position control solenoid valve.
  3. Test the turbocharger vane position control solenoid valve high control circuit for a short to voltage.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 10

10

Test for an intermittent and for a poor connection at the vane control solenoid valve. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 11

11

Measure the resistance of the control circuit between the solenoid valve and the ECM, with a DMM.

Is the resistance more than the specified value?

3 ohms

Go to Step 16

Go to Step 12

12

Measure the resistance of the low reference circuit between the solenoid valve and the ECM, with a DMM.

Is the resistance more than the specified value?

3 ohms

Go to Step 16

Go to Step 13

13
  1. Remove the turbocharger vane position control solenoid valve . Refer to Turbocharger Control Solenoid Valve Replacement .

    2. Important: The solenoid valve may be in 3 different positions:

       • Open--Light is visible through the slot.
       • Closed--The surface of the valve in the slot is smooth.
       • At Rest--The surface of the valve in the slot is serrated.

  2. Observe both sets of slots on the side of the valve. A serrated surface, which is part of the sliding piece visible through the slots, should be fully visible in both slots.

Is the serrated surface visible through the solenoid valve slots?

--

Go to Step 14

Go to Step 17

14
  1. Connect the ECM.
  2. Connect the turbocharger vane control solenoid valve connector.
  3. Turn ON the ignition, with the engine OFF.
  4. Depress and hold the button at the tip of the control solenoid valve.
  5. Command the control solenoid valve ON with the scan tool.
  6. Observe the slot closest to the button when commanding the solenoid valve ON.

Does the spool valve move and open the slot on the vane control solenoid valve when commanded ON?

--

Go to Step 15

Go to Step 17

15
  1. Inspect the turbocharger for debris or damage. Refer to Turbocharger Cleaning and Inspection in Engine Mechanical.
  2. If required, replace the turbocharger. Refer to Turbocharger Replacement in Engine Mechanical.

Is the procedure complete?

--

Go to Step 18

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16

Repair the high resistance in the circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 18

--

17

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

Did you complete the replacement?

--

Go to Step 18

--

18
  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 19

19

Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List

System OK