View Full Version : Case Learn
06-05-2003, 12:19 AM
I purchased the new pcm from pfyc and its says you need a case learn. I went to the dealer and asked if they could do this for me and not the re-flash. The tech. said he cant promise me that the pcm would not get flashed. And all he does is enter the make, module, yr and vin and that's it. He knows nothing of a case learn for after market PCM replacements. The Tech. said it is not possible. What should I ask them to do? If I say can you do a case learn they will reprogram the PCM. what should I ask them to perform w/ the scan tool? So thats the program is not lost?
Thanks For the Help
07-27-2003, 03:53 PM
Don't know if you already got the help you needed, but here's the procedure the dealer needs to perform for you, right off GM's Service and Parts Operations website:
CKP System Variation Learn Procedure
The crankshaft position system variation compensating values are stored in the PCM non-volatile memory after a learn procedure has been performed. If the actual crankshaft position system variation is not within the crankshaft position system variation compensating values stored in the PCM, DTC P0300 may set. Refer to Diagnostic Aids for DTC P0300.
The Crankshaft Position System Variation Learn Procedure should be performed if any of the following conditions are true:
DTC P1336 is set.
The PCM has been replaced.
The engine has been replaced.
The crankshaft has been replaced.
The crankshaft harmonic balancer has been replaced.
The crankshaft position sensor has been replaced.
The scan tool crankshaft position system variation learn function will be inhibited if engine coolant temperature is less than 70°C (158°F). Allow the engine to warm to at least 70°C (158°F) before attempting the crankshaft position system variation learn procedure.
The scan tool crankshaft position system variation learn function will be inhibited if any Powertrain DTCs other than DTC P1336 are set before or during the crankshaft position system variation learn procedure. Diagnose and repair any DTCs if set. Refer to applicable DTCs.
The crankshaft position system variation learn function will be inhibited if the PCM detects a malfunction involving the camshaft position signal circuit, the 3X reference circuit, or the 24X reference circuit. If a malfunction has been indicated, refer to the following list to diagnoses the system or sensor.
DTC P0336 Crankshaft Position (CKP) Sensor Performance
DTC P0341 Camshaft Position (CMP) Sensor Performance
DTC P1374 Crankshaft Position (CKP) High to Low Resolution Frequency Correlation
The scan tool crankshaft position system variation learn function will not be enabled until engine coolant temperature (ECT) reaches 70°C (158°F)
Selecting the Crankshaft Position System Variation Learn Procedure on the scan tool will command the PCM to enable CKP system variation learn fuel cutoff and allow the crankshaft position system variation compensating values to be stored in the PCM. The PCM must detect an engine speed of 5150 RPM (CKP system variation learn fuel cutoff) during the Crankshaft Position System Variation Learn Procedure to store the crankshaft position system variation compensating values and complete the procedure.
Set the vehicle parking brake and block the drive wheels when performing the Crankshaft Position System Variation Learning Procedure in order to prevent personal injury. Release the throttle when the engine reaches the second fuel cut off. Leaving the throttle open during the fuel cut off will allow the engine to decel at an even rate. Once the learn procedure is completed, the PCM will return the engine control to the operator and the engine will respond to the throttle position.
Set the parking brake.
Block the drive wheels.
Ensure the hood is closed.
Start the engine and allow engine coolant temperature to reach at least 70°C (158°F).
Turn off the ignition switch.
Select and enable the crankshaft position variation learn procedure with the scan tool.
Start the vehicle.
Apply and hold the service brake pedal firmly.
Ensure the transaxle is in park.
Increase accelerator pedal position until the fuel cutoff is reached at 5150 RPM. Release the accelerator pedal after the second fuel cutoff has been reached.
The crankshaft position system variation compensating values are learned when the RPM decreases back to idle. If the procedure terminates.
Observe DTC status for DTC P1336.
If the scan tool indicates that DTC P1336 ran and passed, the Crankshaft Position System Variation Learn Procedure is complete. If the scan tool indicates DTC P1336 failed or not run, determine if other DTCs have set. If DTCs other than P1336 are not set, repeat the Crankshaft Position System Variation Learn Procedure as necessary.
08-27-2003, 06:56 PM
so simply leaving the pcm unplugged for 24 hours wont do the trick???
and I have only replaced the harmonic balancer with an aftermarket underdrive pulley
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