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Crankshaft Position Sensor: Testing and Inspection




Crankshaft Position Reluctor Wheel Learn

Circuit/System Description

The engine control module (ECM) monitors the crankshaft position (CKP) sensor signal under specific conditions to calculate errors caused by slight build tolerance variations in the crankshaft, reluctor wheel, CKP sensor, CKP sensor location, and other related components. The calculated error allows the engine control module (ECM) to accurately compensate for reference period variations. The ECM stores the Crankshaft Position Reluctor Wheel Learn values after a Learn procedure has been performed. If the actual crankshaft position variation is not learned in a given time DTC P0315 will set.

The Crankshaft Position Reluctor Wheel Learn feature is used to enable the ECM's quick learn of build tolerance variations. The stored values are cleared and the ECM stores the newly learned variation values after a Crankshaft Position Reluctor Wheel Learn procedure has been successfully performed.

Diagnostic Aids

* CKP Pos. Reluctor Wheel Learn - Command: ON; clears the ECM's learn variation values. Press the ON button once during a Learn procedure.
* CKP Zone 1 Variation Learn Status and CKP Zone 2 Variation Learn Status parameters display:

- Not Learned - until the ECM attempts to calculate the variation value for the respective RPM range.
- Active - when the ECM is calculating the variation value for the following engine speeds:

* Zone 1 - 900 to 1,449 RPM
* Zone 2 - 1,450 to 1,900 RPM

- Complete - when the ECM has successfully finished calculating the variation value for the respective RPM ranges.
- Fail - when the ECM has un-successfully finished calculating the variation value for the respective RPM ranges. More than 1 attempt during an ignition cycle may be needed for the ECM to successfully finish calculating the values.

* A damaged or defective CKP sensor reluctor /exciter ring may prevent the ECM from successfully completing the Crankshaft Position Reluctor Wheel Learn procedure.
* Debris between the CKP sensor and the CKP sensor reluctor /exciter ring may prevent the ECM from successfully completing the Crankshaft Position Reluctor Wheel Learn procedure.
* Monitor the Diesel Particulate Filter (DPF) Regeneration Status parameter, it should remain Inactive when the using the scan tool CKP Pos. Reluctor Wheel Learn procedure.
* Placing the transmission selector in 4th, 5th, or 6th gear may assist in completing the Learn procedure.
* The engine RPM will increase when the torque converter clutch (TCC) is un-applied or unlocked.

Repair Instructions

Note: The Crankshaft Position Reluctor Wheel Learn procedure is required when the following service procedures have been performed, regardless of whether DTC P0315 is set:

* An engine replacement
* An ECM replacement
* An ECM "box swap" with another like vehicle
* A crankshaft harmonic balancer replacement
* A crankshaft replacement
* A flywheel replacement
* An oil pump drive gear replacement
* A CKP sensor reluctor /exciter ring replacement
* A CKP sensor replacement
* Any engine repairs which disturb the crankshaft to CKP sensor relationship

Note:
* The Crankshaft Position Reluctor Wheel Learn procedure may have to be performed up to 4 times before the procedure completes successfully.
* Cycle the ignition to insure the ECM enters a new ignition cycle.

1. Ignition OFF. Verify all vehicle systems are OFF. This may take up to 2 minutes.
2. Ignition ON, engine at idle speed. Observe the DTC information with a scan tool.

• If a DTC, other than P0300-P0308, P0315, P0263, P0266, P0269, P0272, P0275, P0278, P0281, P0284, or P12B3-P12C1 is set, refer to Diagnostic Trouble Code (DTC) List - Vehicle (Diagnostic Trouble Code (DTC) List - Vehicle).
• If DTC P0315 is set, clear the DTC using a scan tool.

3. Select the CKP Pos. Reluctor Wheel Learn procedure with a scan tool.
4. Use the scan tool to: Command On - CKP Pos. Reluctor Wheel Learn procedure. Command State: On
5. Monitor the following parameters with a scan tool. Verify both parameters display: Not Learned.

* CKP Zone 2 Variation Learn Status
* CKP Zone 1 Variation Learn Status

• If both parameters do not display the indicated status, return to step1.

Note: The following steps will cover CKP Zone 2; 1,900 - 1,450 RPM.

6. Select a smooth section of roadway to safely perform the following steps.
7. Safely maintain about 2,500 RPM.
8. When traffic conditions permit, release the accelerator pedal. APP SIGNAL parameter equals 0 %.

Note: Traffic permitting, allow the engine RPM to decrease to between 1,500 - 1,470 RPM.

9. Verify the scan tool CKP Zone 2 Variation Learn Status parameter displays: Active.

Note: When the scan tool CKP Zone 2 Variation Learn Status parameter displays: Complete; the Learn procedure has successfully ended for this RPM range.

10. Verify the scan tool CKP Zone 2 Variation Learn Status parameter displays: Complete.

• If the CKP Zone 2 Variation Learn Status parameter does not display the indicated status, repeat steps 7 - 10, up to 3 more times.

Note: The following steps will cover CKP Zone 1; 1,449 - 900 RPM.

11. Safely maintain about 1,700 RPM.
12. When traffic conditions permit, release the accelerator pedal. APP SIGNAL parameter equals 0 %.

Note: Traffic permitting, allow the engine RPM to decrease to less than 900 RPM.

13. Verify the scan tool CKP Zone 1 Variation Learn Status parameter displays: Active.

Note: When the scan tool CKP Zone 1 Variation Learn Status parameter displays: Complete; the Learn procedure has successfully ended for this RPM range.

14. Verify the following scan tool parameters display: Complete.

• If the CKP Zone 1 Variation Learn Status parameter does not display the indicated status, repeat steps 11 - 14, up to 3 more times.
• If both CKP Zone 1 Variation Learn Status AND CKP Zone 2 Variation Learn Status parameters do not display the indicated status after completing steps 7 - 10 and 11 - 14 a total of 4 times, refer to Diagnostic Trouble Code (DTC) List - Vehicle (Diagnostic Trouble Code (DTC) List - Vehicle) for DTC P0315 for further diagnosis.

15. Engine idling, transmission in Park or Neutral.
16. If you were directed to perform this procedure because DTC P0315 failed, verify that DTC P0315 ran and passed.

• If DTC P0315 failed or did not run, refer to Diagnostic Trouble Code (DTC) List - Vehicle (Diagnostic Trouble Code (DTC) List - Vehicle) for DTC P0315.

17. Ignition OFF. Verify all vehicle systems are OFF. This may take up to 2 minutes.
18. Perform the Diagnostic Repair Verification (Verification Tests) after completing the procedure.

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