So, I'd like to get going on cleaning my wire harnesses that are still an issue (still haven't got a dome light, lights are flickering, etc)

Are there any suggested chemicals I should use? How should I go about cleaning the harnesses? I know the wires are almost 40 years old, but I'd rather not go spending $500 on a dash harness and dealing with another huge project.

Any help is always always appreciated.

 

I did the same thing on my Pontiac and I don't blame you. It's a simple and inexpensive job, but time-consuming. Here are some tips:

1. Make sure you mark every connector and retainer somehow. Obviously you will want to know where everything goes.

2. Once you've extracted the harness, you can unwrap the tape. They make tape that only sticks to itself, available at any hardware store. Make sure you get something that will hold up to heat. I'm sure some fusick's sells something that's very close to OEM.

3. With everything unwrapped, you can check continuity, repair shorts, clean connections, etc. For flat connections (i.e. lugs, spade connectors, ring connectors, packard 56, etc.) I suggest sandpaper or a wire wheel. BE VERY CAREFUL not to nick any wires or take too much material off the connectors. Just get them shiny. Make sure you clean any grounds on the body associated with the harness, too.

4. For other connectors, you can use electrical contact/electronics cleaner. CRC makes it and it's available at any auto parts store or hardware store. I would strongly suggest not cleaning the protective grease where the harness goes to the fuse box. The grease is there to keep it from getting wet (and general protection) and leaving you stranded.

5. Carefully wrap it back up. Don't be afraid to use a lot of tape. That will protect the old harness from heat, but be careful. If you wrap it too much, it will be difficult to route and makes the harness slightly shorter. Use common sense.

I did this to the dash and engine harness on the LeMans and coupled with a 12SI 78A alternator and 2/0 gauge battery cables, I haven't had an electrical problem since!


Good luck!

 

You can clean the wire's plastic casings off by wiping them off with a little lacquer thinner on a rag.
Pick up a roll of the harness wrapping tape (has no adhesive like eletrical tape, not friction tape) and go over the old wrap and wrap anything where it may need it done over. Do a few wraps at the end and tie a knot in it to keep from unwrapping.
I use a little electrical terminal file I picked up at Radio Shack to clean up the terminals if they need it.

 

WD-40 works great on cleaning the wire insulation as well as any glue from the wire wrap etc. Works great on plugs wires also.