Can't reset PCM?
 

I pulled the PCM IGN and PCM Bat codes while it was in the on position, let it sit for about 30 minutes. Came back, turned the car off and replaced the fuses. The car wouldn't crank, the battery was drained because the car has an Amp & subs in it. I got it started, but it started up like normal instead of recalibrating and erasing the SES codes.

Today was the 3rd time I tried it. I tried it 2x yesterday as well. Why isn't it resetting?

That should work, no need to wait 30 minutes, 5-10 should work. What code(s) are you trying to clear? Some set immediately.

Yeah, but it didn't even run poorly when it started up. It's supposed to run funny for a few minutes til it relearns the car. It just cranked right up and was ready to go.

When My duramax goes into limp mode I disconect both batterys neg and turn on the ignition then touch the neg cable to the pos cable, this drains any voltage left in the computers.

Probably not the best way to do it but it works.
Also probably not recomended by GM.

The PCM IS resetting... whether you notice a change or not is immaterial; perhaps the base cal for your car is pretty close. Also, depending on the code, as noted, it may set immeadiately. What is the code?

My friend recommended this method to me earlier.

Eh, I've got a few codes. I'm just going to get the necessary parts and wait til then.