GM 12575172
Crankshaft Position Sensor

Start Crankshaft Position Sensor service by using a scan tool to check powertrain control module dtcs while recognizing that you must check other present dtcs against the diagnostic trouble code (DTC) list. Through the scan tool user interface select the crankshaft position variation learn procedure then monitor the engine fuel cut-off duration. Complete the scan tool sequence by blocking drive wheels while activating the parking brake followed by ignition cycling (OFF to ON) and sustained brake pedal pressure before starting the engine to idle it while turning off the a/c unit then placing the vehicle in park (A/T) or neutral (M/T). During the check the scan tool assesses three essential sensor signals: crankshaft position (CKP), camshaft position (CMP), and engine coolant temperature (ECT). When encountering issues check the relevant dtc for assistance. After the conditions are satisfied enable crankshaft position system variation learn then carefully release the throttle during engine deceleration to allow engine control to restore itself to the operator. The engine speed must be smoothly raised to match the specified rpm before releasing the throttle at the moment fuel cutoff occurs. During the procedure the scan tool shows the message "learn status:" learned this ignition"; engine management will show "learn status: learned this ignition" unless other dtcs are triggered or if this message fails to display. At that point, examine engine performance signs. Refer to the dtc list to analyze any present dtc before proceeding. After completing a learn procedure turn off the ignition for thirty seconds to finalize the process.

Twist the sensor back and forth and pull it straight up to remove it, inspecting for wear.

Replace the sensor.

Turn OFF the ignition for 15 seconds.

Reconnect the CKP sensor electrical connector and reinstall the starter.

Place the CKP sensor back in position and install the CKP sensor bolt, tightening it to 25 N.m (18 lb ft).

Reconnect the CKP sensor electrical connector, reinstall the fuel line bracket and bolt, lower the vehicle, and perform the CKP system variation learn procedure.

Clean the area around the CKP sensor to prevent debris from entering the engine.

Tighten it to 12 N.m (106 lb in).

"Learn Status: Learned this ignition".

Perform the CKP system variation learn procedure.

Lubricate the O-ring with clean engine oil.

Ensure that the mounting surfaces are clean and free of burrs.