GM Crankshaft Position Sensor Learn After ECM/PCM Replacement – P0315 & P1336
Certain General Motors (GM) vehicles require a Crankshaft Position Sensor Learn procedure after replacing the Engine Control Module (ECM) or Powertrain Control Module (PCM).
At ARES Technologies, we provide pre-programmed replacement ECMs and PCMs configured for specific GM vehicle applications. Although our modules are programmed with the appropriate VIN and factory calibration before shipment, certain vehicle-specific learn procedures may still be necessary after installation.
One of these procedures is the Crankshaft Position (CKP) System Variation Learn, also commonly called a Crankshaft Position Relearn or CASE Relearn.
After ECM or PCM replacement, the vehicle may start and operate normally but illuminate the Check Engine Light and store Diagnostic Trouble Code (DTC) P0315 or P1336.
When these codes are associated with an incomplete crankshaft position variation learn, the appropriate learn procedure must be performed before proceeding with further diagnostics or troubleshooting.
What Is a Crankshaft Position Sensor Learn Procedure?
The Crankshaft Position Sensor monitors the position and rotational speed of the engine's crankshaft and sends this information to the ECM or PCM.
The ECM uses these signals for several engine management functions, including ignition timing, fuel injection control, and engine misfire detection.
Small variations in crankshaft rotation can occur due to normal manufacturing tolerances and mechanical characteristics of individual engines.
The Crankshaft Position System Variation Learn procedure allows the ECM or PCM to recognize and store these variations, helping the module accurately distinguish normal crankshaft behavior from actual engine misfires.
After ECM or PCM replacement, this learned information may be missing, even when the replacement module has been correctly programmed.
When Is the Crankshaft Position Learn Required?
On applicable GM vehicles, this procedure may be necessary under the following conditions:
- After ECM or PCM replacement.
- When DTC P0315 is present.
- When DTC P1336 is present.
- After replacing the Crankshaft Position Sensor.
- After certain engine repairs involving the crankshaft or components affecting its relationship with the Crankshaft Position Sensor.
The two commonly associated DTCs are:
| DTC | Description |
|---|---|
| P0315 | Crankshaft Position System Variation Not Learned |
| P1336 | Crankshaft Position System Variation Not Learned (on certain earlier GM applications) |
The procedure may be required after ECM/PCM replacement even when neither DTC is initially present, depending on the vehicle application.
Unlike certain key/immobilizer learn procedures, the Crankshaft Position Learn generally does not prevent the vehicle from starting. The engine can often start and operate before the procedure is completed.
What You Need
- A compatible bi-directional OBD-II scan tool supporting GM Crankshaft Position Variation Learn.
- Access to the vehicle's OBD-II diagnostic port.
- An engine warmed to the operating temperature specified for the vehicle.
A basic OBD-II code reader cannot perform this procedure. A compatible scan tool with the appropriate manufacturer-specific learn function is required.
GM Crankshaft Position Learn Instructions
- Connect the scan tool. Connect a compatible bi-directional OBD-II scan tool to the vehicle's diagnostic port.
- Check for diagnostic trouble codes. Access the ECM or PCM and check for stored DTCs. Other engine-related faults may prevent the learn procedure from completing and should be addressed as required by the vehicle's service information.
- Warm up the engine. Start the engine and allow it to reach the specified operating temperature. Some GM applications require an engine coolant temperature of at least 158°F (70°C).
- Secure the vehicle. Apply the parking brake, block the drive wheels, and ensure the vehicle is in Park (automatic transmission) or Neutral (manual transmission). Turn the air conditioning OFF.
- Locate the learn function. Using the scan tool, access the ECM/PCM functions and navigate to Special Functions, Module Setup, Relearn Procedures, or the equivalent menu.
- Select Crankshaft Position Variation Learn. Choose Crankshaft Position System Variation Learn, CKP Variation Learn, CASE Relearn, or the equivalent function.
- Follow the scan tool instructions. Depending on the vehicle application, the scan tool may require cycling the ignition, holding the brake pedal, or confirming other operating conditions before the procedure begins.
- Perform the engine acceleration. When instructed by the scan tool, increase engine speed as required. On many GM applications, this involves accelerating toward the ECM-controlled fuel cut-off point. Immediately release the accelerator when fuel cut-off occurs or when instructed by the scan tool. Do not exceed the specified engine speed.
- Verify successful completion. Allow the engine to return to idle and confirm that the scan tool reports the learn procedure was completed successfully.
- Complete the procedure. Turn the ignition OFF as instructed by the scan tool, then restart the engine and verify proper operation.
- Check diagnostic trouble codes. Confirm that DTC P0315 or P1336 is no longer active. Clear stored codes if necessary and verify that they do not return.
The exact engine speed, brake pedal requirements, and operating conditions vary by GM vehicle application. Always follow the scan tool instructions and the applicable service procedure.
Important Notes
- The Crankshaft Position Variation Learn may be required after ECM or PCM replacement even when DTC P0315 or P1336 is not present.
- This procedure generally requires the engine to be running and warmed to the specified operating temperature.
- The engine may need to accelerate rapidly during the procedure. The vehicle must be properly secured, and the operator must follow the specified engine speed limits and scan tool instructions.
- Immediately release the accelerator when the required fuel cut-off occurs or the scan tool instructs you to do so.
- Do not attempt the procedure if the engine has an unresolved mechanical condition or another fault that makes the required acceleration unsafe.
- Scan tool menu names, operating conditions, and completion instructions may vary depending on the vehicle application.
- If the procedure fails or DTC P0315 or P1336 remains active, further diagnosis of the Crankshaft Position Sensor, its wiring, related signals, or mechanical components may be necessary.
Pre-Programmed GM Replacement ECMs and PCMs
ARES Technologies specializes in replacement Engine Control Modules (ECMs) and Powertrain Control Modules (PCMs) for Chevrolet, GMC, Cadillac, Buick, and other General Motors vehicles.
Our replacement modules are prepared for specific vehicle applications using OEM-matched hardware, VIN programming, and the appropriate factory calibration. Each module is bench-tested before shipment to help verify proper operation.
Depending on the vehicle application, our replacement ECMs and PCMs may be ready to install and start without additional programming, while others may require key/immobilizer programming or additional learn procedures such as the Crankshaft Position Variation Learn described above.
Whether you're an automotive repair shop, professional technician, or vehicle owner replacing a defective ECM or PCM, ARES Technologies offers pre-programmed replacement modules configured for your vehicle application.
Explore our GM replacement ECMs and PCMs to find the appropriate module for your vehicle.