Circuit Description
The variable nozzle turbocharger (VNT) position sensor is a potentiometer type sensor. The VNT position sensor generates voltage according to VNT position and the generated voltage is input to the engine control module (ECM) for the VNT position sensor signal. The VNT position sensor has the following circuits:
| • | The 5-volt reference circuit |
| • | The low reference circuit |
| • | The VNT position sensor signal circuit |
The ECM supplies 5 volts to the VNT position sensor on the 5-volt reference circuit. The ECM also provides a ground on the low circuit. The VNT position sensor provides a signal to the ECM on the VNT position sensor signal circuit which is relative to the position changes of the VNT. The ECM monitors the VNT position sensor signals for voltage outside the normal range of the VNT position sensor. If the ECM detects an excessively low VNT position sensor signal voltage, this DTC will set.
Conditions for Running the DTC
| • | The ignition is ON. |
| • | The battery voltage is between 10-16 volts. |
Conditions for Setting the DTC
The VNT position sensor signal circuit voltage 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 closes the exhaust gas recirculation (EGR) valve and stops the EGR control. |
| • | The ECM limits VNT control solenoid. |
| • | 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 DTC P2564 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. |
Step | Action | Values | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||||||
1 | Did you perform the Diagnostic System Check - Engine Controls? | -- | Go to Step 3 | |||||
2 |
Is DTC P0641 also set? | -- | Go to DTC P0641 | Go to Step 3 | ||||
3 |
Did the DTC fail this ignition? | -- | Go to Step 3 | Go to Diagnostic Aids | ||||
4 |
Is the DMM voltage within the specified range? | 4.5-5.5 V | Go to Step 6 | Go to Step 5 | ||||
5 |
Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 7 | ||||
6 | Replace the VNT position sensor. Refer to Turbocharger Vane Position Sensor 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 | |||||
