Ok sorry if I dont get this entirely but I just want to make sure before I jump into this. So I am going to buy a toggle switch. I have 2 right now on my blazer, one for fog lights and one spare. It has 3 prongs coming out the back. One neg, one pos, and one for the led I believe. So I take the one wire coming from the HU (parking wire) and put it on the neg on the toggle switch and I am all done right?

 

Your basic toggle switch will have two prongs. One "In" and one "Out"...These are usually labeled 12+ and ACC(accessory)...Dont let this fool you, you can run a ground signal through instead of a 12v signal.....In this case your 12+ would be the p-brake wire coming from the HU...and the ACC would be Ground...

On your 3-Prong L.E.D. Switch. There are 12+, ACC, and Ground...The 12+ and ACC are the same as the 2-prong switch. The ground is only there if you want the L.E.D. to light up. This is not a neccessary hook-up.....

Hope that helps you to understand it a bit better...