Im about to take my Pcm out to send to nelson tune. is it located against the firewall behind the fuse box. I have an 06 2500hd. little black box with two bolts at top and plug at bottom? and also how in the world do u unplug those plugs! every one under the truck i have nearly broke! i have squeezed and done everything i know.[]

 

should be a black plastic cover to the left and down a little from the battery. the pcm is under that. just pull it off, its not bolted. then there should be a "snap" kind of clip that you unsnap (check for more than one). then you will be able to remove the pcm from there and then using i think a 7mm socket, unbolt the plugs from the pcm. then your done. reverse for installation.