If everything is as they should be, then all is well, but if there is a problem somewhere, other than old connectors, the new harness will be cooked too.
I am gonna use this saying which I hate, but seems appropriate here;
When it comes to electricals, "You gotta consider the holistic approach"
I know it sounds pompous, but it puts it in a nutshell.
I have also seen comments about changing the ammeter to a Volt meter and doing away with that much current going through the system, but other members who are knowledgeable in that area can definitely help you.
At any rate, the best of luck!