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 high signal voltage, this DTC will set.
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 more than 4.9 volts.
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 VNT control solenoid operation. |
| • | The ECM closes the EGR valve and stops 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.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||
1 | Did you perform the Diagnostic System Check - Engine Controls? | -- | Go to Step 2 | |
2 |
Did the DTC fail this ignition? | -- | Go to Step 3 | Go to Diagnostic Aids |
3 |
Did you find and correct the condition? | -- | Go to Step 7 | Go to Step 4 |
4 |
Is the resistance within the specified range? | 3.4-4.1ohms at 25°C (77°F) | Go to Step 6 | Go to Step 5 |
Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 5 | |
6 | Replace the VNT position sensor. Refer to turbocharger assembly replacement. Did you complete the replacement? | -- | Go to Step 9 | -- |
7 |
Did you find and correct the condition? | Go to Step 9 | Go to Step 8 | |
8 |
Important: The new ECM must be programmed. Replace the ECM. Refer to Engine Control Module Replacement/Restore Fuel Rate Data . Did you complete the replacement? | -- | Go to Step 9 | -- |
9 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 10 |
10 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |
