Thought Id post this since Im sure a lot of the VPW OBD-II crowd has been faced with the P1336, Crank Sensor Variation Relearn. This error pops up whenever the PCM has been swapped, and the crank position sensor has not been paired with the PCM. The P1336 is a non-maskable, non-clearable code. Even a scan tool will not clear it until a relearn has been done.

So, how do do it? The CASE relearn can be entered by using GM special VPW Mode 0xAE. The flags that control the case relearn are under Submode 0x04. The frame to access and enable the relearn is 6C 10 F1 AE 04 04 04 00 00 00 00. This frame will set the two control flags and allow the CASE relearn logic to run provided the request is sent at least once every two seconds. The relearn is then the usual:

1. Get engine up to operating temp at idle
2. Request case relearn by periodically sending the request frame
3. Press the brake
4. Gradually rev the engine to 4k
5. Release the throttle once the fuel cuts
6. Then shut the vehicle down for a minimum of 30 seconds
7. Key on and clear all DTCs

If the PCM lets you clear the P1336, its now paired to the crank position sensor.

 

To make it easy, I wrote a Tunerpro ADX script that automatically enables the CASE relearn and monitors the feedback. This works with the USB AVT OBD-II cable. I included a screenshot of what the dash looks like.

Important stuff on the dash:

When the relearn is active, the "Learn Active" will turn blue with a "Yes". During this time, a relearn is active.

The CASE wont engage unless "CKP Request OK'd" is "Yes". "No" means that the PCM has rejected the request for one reason or another (either invalid frame for MY or DTCs set). It should stay "Yes" during the whole relearn, but it may turn to "No" afterwards indicating that the learn is complete and the PCM is rejecting another attempt.

Status Flags:

The following flags are only supported by pre '00 MY PCMs:
"Cool temp too Low" - Engine not up to temp
"Too many attepts" - The relearn has exceeded the # of allowed attempts.

The "Errors Detected" sets if a P1336 is present after a relearn is done, but does not seem to cause the PCM not to pair to the sensor. The others are more involved, but should not be set. If they do set, then something is wrong with either the crank encoder or the cam or crank sensor.

I tried this on my 99 and it worked. I have not tried it on newer MY VPW PCMs, but it should still work ok. The OBD logic in them seems pretty similar to my 99 vortec PCM from which this is based on.

 

Awesome!!!

 

Actually this is really great news for me. The LQ4 I'm rebuilding right now to swap into my 99 Burb will be needing to have the 24x ring replaced and I was wondering what to do if the 0411 pcm (which I just picked up saturday) will set a CKP code like I've heard about.
Now thats one more concern out of the way for this swap.

thanks a million for sharing your work.

 

I wanted to add my thanks, as the 411 swap in my LT1 is setting this code.

 

Hey demented, I just tried this on my 2001 411 and I can't get the active learn blue "yes" to turn on. I get all green falses and a yes, brake on, rev to 4K and hold. Nothing happens. Am I missing something on how the adx is supposed to work?

Thanks

 

Let me try it on my '411 PCM. The Mode AE, device control, is a custom GM OBD mode, so they may have changed how it works, or how often the frame needs to be sent.

 

Ok just verified on the bench that they changed the submode and flags needed to activate the CASE relearn on the '411. The PCM rejects the existing frame. I'll have to trace the code and see what it is now.

 

I loaned my Tech 2 to a friend. I should have it back this week and can then sniff to see what its issuing for a 2001 CASE relearn.

 

Any idea what it changed to for the 01 411 PCM?

 

I know it's been a while since this post. This is the only info I could find on this. I was wondering if anyone has tried this on a 2002 12209614 pcm.

 

I just finished my L31 swap and need help doing the crank relearn. my cousin has a OTC Genisys that has the procedure on it, but i'm getting a error message to set the parking brake. seen on the forum elsewhere that you can ground out wires on pins 32 and 34, on the blue c80 connector. says that will make the pcm think its set, but i dont have a wire going to pin 34. any ideas? Or would it be easier to just get a custom OBD-ll wire and load the file given above?

 

Do you need to set the PARKING brake or the FOOT brake?

1. Get engine up to operating temp at idle
2. Request case relearn by periodically sending the request frame
3. Press the brake
4. Gradually rev the engine to 4k
5. Release the throttle once the fuel cuts
6. Then shut the vehicle down for a minimum of 30 seconds
7. Key on and clear all DTCs