Crankshaft Position Variation Learn Procedure with a Scan Tool

The Crankshaft Position (CKP) system variation learn procedure is a critical step in vehicle maintenance, particularly after specific engine repairs or component replacements. This procedure ensures the engine control module (PCM) accurately reads crankshaft position, which is vital for optimal engine performance and preventing diagnostic trouble codes (DTCs). Utilizing a scan tool makes this process straightforward and precise.

When is the CKP System Variation Learn Procedure Required?

Performing the CKP variation learn procedure is essential in several scenarios to maintain the correct relationship between the crankshaft and the CKP sensor. These situations include:

• Engine Replacement: When a new or different engine is installed.
• Control Module Replacement: If the PCM or engine control module is replaced.
• Crankshaft Balancer Replacement: After replacing the crankshaft balancer.
• Crankshaft Replacement: Following the replacement of the crankshaft itself.
• CKP Sensor Replacement: Whenever the crankshaft position sensor is replaced.
• Engine Repairs Disturbing CKP Sensor Relationship: Any engine work that might alter the alignment or distance between the crankshaft and CKP sensor.

Even if DTC P0315, which specifically relates to the CKP system variation not learned, is not present, completing this procedure after these services is crucial for preemptive maintenance and system accuracy.

Prerequisites and Conditions for CKP Learn Procedure

Before initiating the CKP System Variation Learn procedure with a scan tool, ensure the following conditions are met. These conditions are monitored by the PCM, and a scan tool will typically indicate any inhibiting factors:

• CKP Sensor Activity: The scan tool should confirm proper operation of the CKP sensors. Any CKP sensor related DTCs must be addressed first.
• Camshaft Position (CMP) Signal Activity: Similarly, the camshaft position sensor signal needs to be active and functioning correctly. Resolve any CMP sensor DTCs beforehand.
• Engine Coolant Temperature (ECT): The engine must be at a sufficient operating temperature. If the engine coolant temperature is too low, allow the engine to idle until it reaches the correct temperature.

Step-by-Step Guide to Perform the CKP Learn Procedure

Follow these steps to execute the Crankshaft Position System Variation Learn procedure using a scan tool effectively:

1. Install and Connect Scan Tool: Connect a compatible scan tool to the vehicle’s diagnostic port and establish communication with the powertrain control module (PCM).

2. Check for Existing DTCs: Using the scan tool, check for any present DTCs in the PCM. Address any DTCs, except P0315, before proceeding with the CKP learn procedure. Refer to the vehicle’s diagnostic trouble code list for troubleshooting other codes.

3. Initiate CKP System Variation Learn Procedure:

   • Secure Vehicle: Block the drive wheels and firmly set the parking brake to ensure safety.
   • Parking Brake Set: Confirm the parking brake is engaged.
   • Do Not Press Brake Pedal (Initially): Keep the brake pedal released until instructed.
   • Ignition Cycle: Cycle the ignition from OFF to ON position.
   • Apply and Hold Brake Pedal: Now, apply and hold the brake pedal throughout the procedure.
   • Start and Idle Engine: Start the engine and let it idle.
   • Turn Off Air Conditioning (A/C): Ensure the air conditioning system is turned OFF to minimize engine load.
   • Transmission in Park/Neutral: The vehicle must be in Park (automatic transmission) or Neutral (manual transmission).
   • Wide Open Throttle (WOT) Acceleration: When prompted by the scan tool, rapidly accelerate the engine to wide open throttle (WOT).
   • Release Throttle at Fuel Cut-Off: Immediately release the throttle when the engine begins to decelerate due to fuel cut-off. It’s crucial to release the throttle promptly at this point.

4. Verify Learn Status: Observe the scan tool for the “Learn Status” indication.

   • “Learned this Ignition” or “DTC P0315 passed”: This confirms the CKP variation learn procedure is successfully completed.
   • “DTC P0315 failed” or “did not run” or other DTCs: If the procedure fails, or any other DTCs are present, consult the vehicle’s diagnostic trouble code list and perform the necessary diagnostic steps.

5. Finalize Procedure: After successful completion, turn the ignition OFF for at least 30 seconds. This step is essential to save the learned CKP system variation values into the PCM memory permanently.

By following these steps carefully with a scan tool, you can accurately perform the crankshaft position variation learn procedure, ensuring proper engine operation and avoiding potential issues related to CKP sensor readings.