wiring problem

Bought 61 vette, older restoration. Painless wiring was used. I replaced battery. It had 2 extra wires connected to pos post. Upon trying to start car, one wire shorted and melted. I traced it under pass dash. It was connected to 4 more wires. I put heavier wire from battery with 20 amp fuse. Reconnected and fuse blew. Not sure what to do. Don't want to totally remove wiring harness. Wires were blk/wht.

My recommendation would be to start by disconnecting all 4 of the wires that are fed by that circuit, then measure each one to ground. If you're lucky, only 1 of those wires will have a low resistance path to ground. Once you identify that one, trace that wire to determine what it powers. Or leave it disconnected, reconnect the other three wires, then see what doesn't work and that's probably the circuit of issue. Maybe during some reassembly a screw was run through a power wire, or when something like the seat was mounted it pinched and shorted a wire, etc.

I thought Painless wiring was the type that had writing on the wires for what circuit they went to. Although if this wire to the battery did not have fuse protection prior to you adding the fuse, it's probably not something that came from Painless to begin with....

-Rod

Thanks for the response. Not much of an electrician. How do I "check to ground"?

In a low Ohm setting (20/200) ,ground your meters black minus lead to body/chassis and red lead to the wiring being tested. Look for one reading very low. (Will be 0 Ohms if dead short)