under dash wiring

I echo what has previously been said because i suffered similar

the under dash wiring will be fine. unless there has been a catastrophic. melting and smoke situation.
(Mr hack it in with sharks teeth connectors stuff can be easily rectified)

In the main its the last six inches of un wrapped wire and the nasty black tarnish or green powder on the connectors that cause this

an afternoon with a small brass wire brush, some dainty needle nose pliers and a tub of vaseline... sounds kinda wrong but does get you satisfaction...eventually