Performing a crankshaft position relearn, sometimes referred to as CKP relearn or CASE relearn, is a crucial procedure after certain automotive repairs or replacements. This process ensures your engine management system accurately reads the crankshaft position, which is vital for proper engine timing and performance. Using an Obd2 Scanner With Crankshaft Relearn capabilities simplifies this task significantly. This guide outlines the necessary steps and conditions to successfully complete a crankshaft relearn using your OBD2 scan tool.
Pre-Conditions for Crankshaft Relearn
Before initiating the crankshaft relearn procedure with your OBD2 scanner, it’s imperative to ensure several conditions are met. Failure to adhere to these preconditions will prevent the procedure from running successfully. Pay close attention to the following diagnostic trouble codes (DTCs) and engine parameters:
Diagnostic Trouble Codes (DTCs):
None of the following DTCs should be present in your vehicle’s computer system. If any of these codes are active, address them first before attempting the crankshaft relearn.
- P0335 Crankshaft Position (CKP) Sensor A Circuit
- P0336 Crankshaft Position (CKP) Sensor A Performance
- P0341 Camshaft Position (CMP) Sensor Performance Bank 1 Sensor A
- P0342 Camshaft Position (CMP) Sensor Circuit Low Bank 1 Sensor A
- P0343 Camshaft Position (CMP) Sensor Circuit High Bank 1 Sensor A
- P0117 Engine Coolant Temperature (ECT) Sensor Circuit Low
- P0118 Engine Coolant Temperature (ECT) Sensor Circuit High
- P1539 Air Conditioning (A/C) Clutch Feedback Circuit High Voltage
- P1546 Air Conditioning (A/C) Clutch Feedback Circuit Open
- P0705 Transmission Range (TR) Switch Circuit
- P0706 Transmission Range (TR) Switch Performance
- P1810 Transmission Fluid Pressure (TFP) Position Switch Circuit
- P1825 Internal Mode Switch-Invalid Range
Engine Parameters:
In addition to the DTCs, the following engine parameters must be within the specified ranges:
- Engine Coolant Temperature (ECT): Must be between 150°F and 220°F (approximately 65°C to 104°C). Ensure the engine is warmed up to operating temperature.
- Engine RPM: Must be below 2400 RPM before starting the procedure.
- Throttle Position Sensor (TPS): Must read 0%, indicating a closed throttle position.
- Vehicle Speed Sensor (VSS): Must read 0 mph, meaning the vehicle is stationary.
Vehicle Preparation:
Before starting the procedure with your OBD2 scanner, take these preparatory steps:
- Parking Brake: Firmly apply the parking brake to prevent vehicle movement.
- Transmission Position: Place the transmission in Park (P) for automatic transmissions or Neutral (N) for manual transmissions.
- Accessories: Turn off all unnecessary accessories such as headlights, air conditioning, and radio to minimize electrical load.
- Brake Pedal: Keep your foot firmly pressed on the brake pedal throughout the procedure for safety.
Step-by-Step Crankshaft Relearn Procedure with an OBD2 Scanner
Once all the preconditions and preparations are complete, follow these steps to perform the crankshaft relearn using your OBD2 scanner:
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Connect your OBD2 Scanner: Plug your OBD2 scanner into the vehicle’s OBD2 port, typically located under the dashboard on the driver’s side. Power on the scanner and establish a connection to the vehicle’s computer system.
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Navigate to DVT or Diagnostic Functions: Using your OBD2 scanner’s interface, navigate to the Diagnostic Test (DVT) tab or the section for special functions or service procedures. The exact menu names may vary depending on your scanner brand and model.
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Select Controller: Within the DVT or diagnostic functions menu, you will likely need to select the engine control module (ECM) or powertrain control module (PCM). This is the controller that manages the crankshaft relearn function.
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Activate the Procedure: Look for an “Activate” or “Start” button or option within the ECM/PCM menu. Select this to initiate the diagnostic functions.
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Access Learning Subtab: After activating, you should find a “Learning” or “Adaptation” subtab. Navigate to this subtab.
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Select CASE or Crankshaft Relearn: Within the Learning subtab, locate and select the option labeled “CASE Relearn” or “Crankshaft Relearn.” CASE stands for Crankshaft Angle Sensor Error, and this is the function you need to execute.
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Initiate RPM Increase: Follow the on-screen prompts of your OBD2 scanner. Typically, you will be instructed to “open throttle to increase RPM above 4000 within 10 seconds.” Smoothly and quickly depress the accelerator pedal to raise the engine RPM above 4000 RPM within the specified timeframe.
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Observe for Stumble/Misfire and Release Throttle: As the engine RPM passes 4000 RPM, carefully listen and feel for a stumble or misfire. This indicates that the relearn procedure is engaging. Immediately release the throttle pedal as soon as you detect the stumble or misfire.
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Engine Spindown and Idle: Allow the engine RPM to naturally decrease and return to idle speed. Do not touch the accelerator pedal during this spindown process.
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Turn Off Engine and Wait: Once the engine has returned to a stable idle, turn off the engine completely. Wait for approximately 15 seconds. This allows the ECM/PCM to finalize the relearn process.
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Deactivate (Optional): While waiting for 15 seconds, you can typically use your OBD2 scanner to click a “Deactivate” or “Stop” button within the scanner interface to conclude the diagnostic session on the tool.
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Verify Completion: After the 15-second wait, restart the engine. Use your OBD2 scanner to check for any DTCs. If the crankshaft relearn was successful, no DTCs related to crankshaft position should be present, and the relearn procedure should be complete.
Conclusion
Performing a crankshaft relearn is essential after certain engine work. Utilizing an OBD2 scanner with crankshaft relearn function makes this process straightforward. By carefully following these preconditions and step-by-step instructions, you can effectively complete the crankshaft relearn and ensure optimal engine performance and accurate readings from your engine management system. Always refer to your specific OBD2 scanner manual and vehicle service information for any specific instructions or variations in the procedure.
