Have you done a resistance test on the harness? If it is different from the other harnesses it is probably bad, otherwise it is the connectors.
Same thing happened to me. Check out my other posts and good luck.

 

Oh, BTW. Take your breaker bar or ratchet down to Home Depot and go to the plumbing dept. Find a 1 and 2 foot long piece of iron pipe that just fits over the handle to your wrench When breaking a tough bolt just slide the pipe over the end of the wrench handle to elongate it which give you much more leverage. Cheater bars are much cheaper than buying large wrenches and work even better as you can adjust the length to fit the situation. Saves a lot of cracked and bleeding knuckles as well.

 

Not much to add to this thread, I just want to say NEVER use WD-40 to "loosen" a bolt. It actually lubricates the bolt and you have an increased chance of slipping off.

You need to use a penetrating liquid like liquid wrench or PBlaster to loosen a nut.

 

great advice Mike, never really thought about it.......