Performing a crankshaft position relearn, sometimes referred to as CASE relearn, is a crucial procedure after certain engine repairs or modifications. This process ensures the engine control module (ECM) accurately reads the crankshaft position, which is vital for optimal engine performance and preventing misfires. Using an Obd2 Scanner With Crankshaft Relearn capabilities simplifies this process significantly. This guide will walk you through the steps and prerequisites for a successful crankshaft relearn.
Before initiating the crankshaft relearn procedure with your obd2 scanner, it’s imperative to ensure that certain conditions are met and no interfering diagnostic trouble codes (DTCs) are present. Failure to address these prerequisites will prevent the relearn process from running correctly. Specifically, the following DTCs must be clear:
- 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
In addition to the absence of these DTCs, the following conditions must be satisfied to proceed with the crankshaft relearn using your obd2 scanner:
- Engine Coolant Temperature (ECT): Must be between 150°F and 220°F (65°C – 104°C). This ensures the engine is at a proper operating temperature for accurate sensor readings.
- Engine RPM: Must be below 2400 RPM before starting the procedure. This is a safety measure and ensures the procedure starts under controlled engine speed.
- Throttle Position Sensor (TPS): Must read 0%. This indicates a closed throttle position, which is necessary for the procedure to initiate correctly.
- Vehicle Speed Sensor (VSS): Must read 0 mph. The vehicle must be stationary for the relearn procedure.
- Parking Brake: Should be applied for safety.
- Transmission: Must be in Park or Neutral.
- Accessories: Turn off all unnecessary accessories (A/C, radio, lights) to minimize electrical load on the system during the procedure.
- Brake Pedal: Keep your foot firmly on the brake pedal throughout the initial steps.
Once all the above prerequisites are confirmed, you can proceed with the crankshaft relearn procedure using your obd2 scanner. The following steps outline a general procedure, and specific steps may vary slightly depending on your obd2 scanner model. Always refer to your scanner’s user manual for precise instructions.
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Connect your OBD2 Scanner: Plug your obd2 scanner into the OBD2 port of your vehicle.
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Establish Communication: Turn the ignition key to the “ON” position (engine off). In your obd2 scanner interface, typically you’ll need to select a “connect” or similar button to establish communication with the vehicle’s ECM.
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Navigate to DVT Tab: Within your obd2 scanner menu, locate and navigate to the “DVT” (Diagnostic Test) tab or a similarly named section that allows access to vehicle systems and tests.
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Select Controller: Choose the appropriate controller, usually “Engine Control Module (ECM)” or Powertrain Control Module (PCM), from the list of available controllers.
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Activate Learning Function: Within the ECM/PCM menu, look for an “Activate” button or option. Clicking this will typically lead you to a submenu containing various learning or calibration procedures.
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Access CASE Relearn: In the learning submenu, find and select the “CASE” or “Crankshaft Relearn” option. This is the specific function to initiate the crankshaft position relearn procedure.
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Initiate RPM Increase: Follow the on-screen prompts on your obd2 scanner. Typically, you will be instructed to rapidly increase the engine RPM to above 4000 RPM within 10 seconds by quickly opening the throttle.
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Observe Engine Response: As you increase RPM, listen and feel for a stumble or misfire. This indicates the ECM has successfully learned the crankshaft position variation. Immediately upon noticing the stumble/misfire, release the throttle.
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Engine Spindown and Idle: Allow the engine RPM to decrease and stabilize at idle speed.
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Turn Off Engine and Wait: Once the engine reaches idle, turn the engine off and wait for 15 seconds. This allows the ECM to finalize the relearn process.
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Deactivate (Optional): While waiting the 15 seconds, you may have the option on your obd2 scanner to click a “Deactivate” button to end the active test session.
After completing these steps using your obd2 scanner, the crankshaft relearn procedure should be successfully finished. This process ensures accurate crankshaft position readings, leading to improved engine performance, smoother operation, and the elimination of potential misfire issues. Always verify the procedure with your specific obd2 scanner manual and vehicle service information for the most accurate and safe execution.
