I have some frayed wires 1/3 of an inch after the connector on my headlamps. I followed the wires all the way to the giant gathering at the rear of the firewall. I'm gathering that it would be a bitch to have to go through all of that to change the messed up wires. I'm not an electrician but can you just cut the wires even, remove the broken ends from the plastic harness thing and re-attach it to the good wires? Is it that simple?

 

Sort of.

These are relatively high current wires, so the splice should be soldered.
Frayed wires are usually tarnished, so solder does not flow well.
You need shinny clean copper at the exposed ends to make a good solder joint.

 

The right crimping tool and the right butt/window/enviro splice will work. I've crimped 10 gauge stuff on my car with no problems. Most guys just don't know how very difficult it is to fully saturate (tin) a stranded copper wire larger than about 14 gauge, even with flux. Your choice, though

I would cut the damaged area out, then crimp the freshly stripped ends with the proper butt splice, then environmentally seal it (heat shrink, RTV, whatever floats your boat). But that's me...

 

Alright. I'll give it a shot the next time I have some free time. If I goof it up I'll let you know