Test Procedure

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AK1 PRELIMINARY DIAGNOSIS FOR DTC P0046

NOTE: Refer to Figure for PCM and component connector at the beginning of this pinpoint test.

Carry out a visual inspection.
Retrieve and record all DTCs.
Record the freeze frame data.
Clear all DTCs.
Carry out the on-demand self-test.

Is DTC P0046 present?

Yes	No
GO to AK2.	UNABLE to duplicate the condition. CHECK for a loose connection, and damaged or corroded terminals. WIGGLE the harness attempting to recreate the fault. REPAIR as necessary. REFER to SYMPTOM CHARTS - 6.0L DIESEL if a driveability concern exists.

AK2 DIAGNOSTIC TROUBLE CODE (DTC) P0046

Possible causes:
- control circuit open
- control circuit shorted to voltage
- control circuit shorted to ground
- VGT actuator
- PCM.
Key OFF.
Disconnect the VGT actuator.
Key ON, engine OFF.
Measure the voltage between the VGT actuator pin 1, harness side and ground.

Is the voltage greater than 10.5 volts?

Yes	No
GO to AK3.	REPAIR the open circuit. CLEAR the DTCs. REPEAT the self-test.

AK3 CHECK THE VGT ACTUATOR

Key OFF.
Access the output state control.
Connect a test lamp between the VGT actuator pins 1 and 2, harness side.
Key ON, engine OFF.
Access the VGT PIDS.
Command the VGT to less than 10% duty cycle.
Command the VGT to 85% duty cycle.

Does the test lamp go out as the VGT duty cycle is driven low and illuminate as the duty cycle is driven high?

Yes	No
GO to AK7.	GO to AK4.

AK4 CHECK THE VGT CONTROL CIRCUIT FOR A SHORT TO VOLTAGE

Key OFF.
Disconnect the test lamp.
Disconnect the PCM engine harness electrical connector.
Key ON, engine OFF.
Measure the voltage between the VGT actuator pin 2, harness side and ground.

Is the voltage less than 0.2 volts?

Yes	No
GO to AK5.	REPAIR the short in the control circuit. CLEAR the DTCs. REPEAT the self-test.

AK5 CHECK THE VGT CONTROL CIRCUIT FOR A SHORT TO GROUND

Key OFF.
Measure the resistance between the VGT actuator pin 2, harness side and ground.

Is the resistance greater than 10,000 ohms?

Yes	No
GO to AK6.	REPAIR the short in the control circuit. CLEAR the DTCs. REPEAT the self-test.

AK6 CHECK THE VGT CONTROL CIRCUIT FOR AN OPEN

Measure the resistance between the VGT actuator pin 2, harness side and the PCM engine connector pin 10, harness side.

Is the resistance less than 5 ohms?

Yes	No
INSTALL a new PCM. CLEAR the DTCs. REPEAT the self-test.	REPAIR the open in the control circuit. CLEAR the DTCs. REPEAT the self-test.

AK7 CLEAN THE VGT ACTUATOR VALVE AND RETEST

CAUTION: The VGT actuator valve is sensitive to contamination. All work areas must be clean before starting this procedure. Do not allow contamination to enter the valve ports, cam follower, or turbocharger housing. Handle the VGT actuator by the solenoid body only. Do not attempt to wipe oil off the valve. Do not let the valve come in contact with materials that could contaminate the valve mechanism.

CAUTION: Use only the Carburetor Tune-Up Cleaner PM-2 to spray the actuator valve. Brake cleaner or other solvents may damage the actuator valve.

Remove the VGT actuator from the turbocharger assembly.
NOTE: Do not spray the zinc coated larger diameter housing, or electrical connector.
Spray the valve with Carburetor Tune-Up Cleaner PM-2 while pressing the cam follower (tip of the actuator).
Install the VGT actuator and connect the VGT connector.
Key ON, engine running.
Access the output state control.
Access the VGT PID.
Increase the commanded engine speed to 1,250 RPM using output state control. The calibration may limit the actual RPM between 1,150 and 1,200 RPM.
Increase the VGT duty cycle to greater than 70%.
Decrease the VGT duty cycle to 0%.

Does the turbocharger pitch change when the VGT duty cycle is increased and decreased?

Yes	No
The system is operating correctly at this time. The concern may have been caused by a contaminated VGT actuator valve. CHANGE the oil and oil filter assembly.	INSTALL a new VGT actuator. CLEAR the DTCs. REPEAT the self-test.