Cannot get my 2003 HD2500 to case relearn

[gnnova]

I've got a 2003 HD2500 with a misfire on #1 and #6 cylinders around 2200 and above at light load.  I'm trying to do a case relearn with a Determinator scanner sold through Mac tools.  It will go though the test fine with a fuel cutoff but will give me a test failure at the end.  It has a aftermarket radio that I removed it and the alarm interface it is connected to but the test still fails.  Anyone have any ideas why I cannot get it to work?

[newdude]

What exactly do you mean by a "case relearn"?

 

What engine is in the truck as well? 

[gnnova]

Engine is a 6.0 with a 4l80e 4X4.  Sometimes it is called a crankshaft relearn.  It's where you perform a procedure with a scanner to calibrate the crank and cam sensors to the PCM.

[newdude]

25 minutes ago, gnnova said:

Engine is a 6.0 with a 4l80e 4X4.  Sometimes it is called a crankshaft relearn.  It's where you perform a procedure with a scanner to calibrate the crank and cam sensors to the PCM.

 

Do you have any codes before doing the relearn?  Procedure from GM shows that all codes set should be resolved aside from a P0315 which is for crankshaft variation data not stored.  This would pop up after replacing the sensor most likely. 

 

[gnnova]

No codes other than P0300 and it was reset prior to the performance of the procedure.

[sefiroxx]

Did you reset the code, or allow for the cover to expire. If reset, the misfire may be causing problems with the relearn.

[gnnova]

I reset it prior to performing the procedure.

[carkhz316]

I had the same truck as you OP. I had trouble getting it to take a few times with HP tuners. I can't remember what I did differently, but make sure you're following the instructions to a "T". And for the heck of it, make sure the park brake is set. I know it sounds dumb, but it wasn't until I verified everything a few times before it finally worked.

[gnnova]

I know I followed the procedure because it is displayed in each step on the scanner.  You did give me an idea to make sure the switches are picking up which could cause issues.  But I'm thinking that something is staying active that is preventing the scanner from completing the procedure.  That's why I started the thread to see if anyone has seen this.

[gnnova]

I forgot, yes the parking brake was set in the beginning of the procedure as required.