Join Date: Mar 2002
Location: Austin, TX, USA
The problem with 30 year old harnesses is that the insulation gets brittle. Also, I haven't seen too many that weren't hacked up by 30 years of stereo installs, and other aftermarket goodies. Another common problem is the fuse tabs. They weren't heavily plated and almost all loose their spring tension and corrode.
If you must rewire, I'd strongly consider the aftermarket. There are at least three major suppliers of harneses. Some are very close to factory. Others bare little resemblance to factory, but are better in some ways because of extra circuits. If you buy aftermarket, keep the old harness around. You may end up having to use some of the connectors on it. Also, the old harness will serve as a good template when installing the new one.
No matter which way you go. Be sure to seal up the connections at the fuse panel and other places where water and road grime can hide and degrade the connections. I plan on doing a solvent wipe down on mine and reinstalling until I get the cash to replace it.