Dead Short in starting circuit

[GamingKing]

Ok so for a few weeks now when i would drive my truck say down the highway to work or gas station, if i turn the truck off and try to restart it it wouldnt start. When its cold it starts fine no issues but when its hot it will very slowly turnover almost like a dead battery. If i let cool for 10 - 15 mins it'll start reluctantly or just pop start it and she will run fine.
Earlier this week I figured my battery is going but i load tested it and it passed with flying colors and then the next day it wouldnt start at all. Turn the key and all i get is one loud click so i said there goes the starter. Switched to a brand new one but still the same 1 click. Changed out the starter relay same thing no difference. So i pulled the new starter out and brought it and the old starter to a shop got them tested and they both passed. I kept the new one anyways but now Im stuck.
So far we replaced all the cables from the battery to the relay and from there down to the starter. Cleaned the batt terminals, checked the grounds and even ohmed the cables. When the key is turned all the wires visibly jump from the current so Im assuming a dead short somewhere but i cant locate it. any help would be great thanks guys.

 

[kimcrwbr1]

When the engine is cold put a wrench on the crankshaft bolt and turn the crank. Then after the engine is hot and wont start try and turn the crank again and see if it is hard to turn. Make sure the key is off when turning the crank or just disconnect the battery when you put your hands down there. If so it could be several things, loosen the tension on the belt and check the alternator, power steering pump, any idler pullys and crank again to determine where it is seized. Do you smell fuel in the oil? It sounds like you have done everything you can for the starting circuit try and turn it over by hand when it stops working.

 

[Scrambler82]

Dd you say you changed the starter and relay ?

Also check the ground connection of the relay.

If all else fails, using battery jumper cables, connect a jumper cable from one of the starter mounting bolts back to the negative side of the battery.
Try to start it then.

Sometimes when an engine is hot it will draw more current which n turn affects the grounding, that may well be where the one loud click is coming from...

Just thinking out loud.

 

[kimcrwbr1]

Bend the cables end to end looking for weak spots also have someone turn the key for you when it is dark out maybe you can see the spark. When it dont start feel for hot cables or cable ends?