I'm installing the battery tray and I see a grounding wire coming from the cab towards the PCM I don't no actually where it goes . This where is laying right now I'm pretty sure the grounds to the frame but I don't know where can anyone tell me where this wire grounds to pleas

 

That wire I don't think is a ground. It should be the positive wire to run the power to inside the truck.

 

how do I make sure that a positive wire I don't want hook up the wrong wire to the battery lol

 

That’s the positive lead to the drivers positive post.

Check one, don’t hook it up and no power to anything in the truck. Nada.

Check two, set your multimeter to ohms or continuity, attach one lead to the eyelet, touch some other positive contact, light bulb (switched on) fuse panel, whatever.

 

Also if you trace that cable backwards past the reservoir you’ll find there are fusible links spliced in there. Fusible links are always on positive cables, never negative.