If you’re tackling a GM crankshaft position relearn, you’ll need a compatible scan tool. While various options exist, ensuring your tool can execute this specific procedure is crucial. This article outlines the requirements and steps for a successful GM crankshaft position relearn using a suitable scan tool.
Certain diagnostic trouble codes (DTCs) must be absent for the crankshaft position (CKP) relearn procedure to initiate. These include codes related to the crankshaft and camshaft position sensors (P0335, P0336, P0341, P0342, P0343), engine coolant temperature sensor (P0117, P0118), A/C clutch feedback circuit (P1539, P1546), and transmission range switch and fluid pressure (P0705, P0706, P1810, P1825).
Before starting the relearn procedure, ensure the engine coolant temperature (ECT) is between 150°F and 220°F. The engine RPM must be below 2400, the throttle position sensor (TPS) at 0%, and the vehicle speed sensor (VSS) also at 0. Engage the parking brake, place the transmission in Park or Neutral, and turn off all accessories. Keep your foot on the brake pedal.
Connect your scan tool and establish communication with the vehicle. Navigate to the Datastream or similar tab within the software, select the appropriate controller (usually the Powertrain Control Module or PCM), and click “Activate” to initiate the CKP relearn function.
Next, locate the “Learning” or “Special Functions” subtab and select “CASE” or “CKP Relearn.” You will be prompted to quickly open the throttle to raise the engine RPM above 4000 within a 10-second window. As soon as you hear or feel a stumble or misfire, immediately release the throttle.
Allow the engine to return to idle. Once idling, turn off the engine and wait for 15 seconds. During this waiting period, you can typically click “Deactivate” on the scan tool to conclude the relearn procedure. A successful relearn will clear any related DTCs and restore proper engine operation. Remember to consult your specific vehicle’s service manual for detailed instructions and any variations in the procedure.
