Let's start from scratch. When you turn the key to start does the starter crank the motor or will it only do it when jumping the fender relay

 

OK then that's not the problem then

 

Starter relay is wired correctly. There's probably at least one other wire on that "ganged" terminal, that supplies main power to the underhood fuse box (and, ultimately, the rest of the truck).

It's normal for the glow plug relay to click ONCE when you turn the key to RUN. If it's a cyclic or repeating click, that's NOT normal. Once again, an indicator of a voltage problem caused by a weak connection or weak batteries.

There may be something wrong with the alternator, causing the batteries to discharge, but the alternator is not directly related to starting the engine (since, of course, it's not turning until the engine starts).

 

OK. You turn the key to start and it acts like its has a short. And then I loose all power. When I jump the fender relay it does turn but then it drains the battery fast, I don't know why tho

 

Have you LOAD tested BOTH batteries, in isolation from one another, as mentioned above? These are classic symptoms of weak batteries or weak main power connections.

 

OK. How do you "load test" the batteries? I've never had to do it that's why I'm asking

 

Isn't that when you put it in another vehicle and turn everythin on?

 

No. You disconnect one of the negative terminals, so the two are not in circuit together. Then connect a load tester to one battery. Cheapo version - 6 Volt/12 Volt Battery Load Tester . Fancy-cheapo version - 500 Amp Carbon Pile Load Tester . They probably have the cheapo version available for "loan" (you put up a deposit) at your nearby chain auto parts store. Or, you can pull each battery out and haul them into the store for the same test.

But look closely at main connections / wires - at the batteries, where the battery negative cables ground to the engine block, general condition of those cables. They're bigeffin' cables, something like 2/0 gauge, and carry a LOT of load when you turn the key. Any damage to them can give you the kind of fits you're describing.

When you turn the key to RUN (but NOT to START), does the truck "act normal"? GP relay clicks loudly ONCE, WTS light comes on for 5-10 seconds, you can run the radio, wipers, etc, no smoke or sparks or scary stuff coming from any wires / connections? No repeated clicks? That's the part that's still not clear.

 

I can probably get a load tester. But yea I checked the ground cables and they are like "brand new" condition I wanna say because there isn't any corrosion on the copper wire or bare spots in the insolatio. You can run the wipers lights radio ect ... When you have it in run position.