Senior Tech Team
Join Date: Aug 2007
Location: The Sunny South
Re: My harness is in a box
If you decide to attempt to reuse the old harness, then FIRST lay it out on a large flat surface and carefully examine it. If you find only obvious chop/cuts at the usual "Last guy was an idiot" spots (like radio wiring) and the rest of the harness and connectors look unmelted and decent, it may be a candidate for reuse.
Here's my eleven step process to restore a usable OEM harness:
1. I take the time to electrically verify all wires with a meter - FIRST. I use a VTVM, because a VTVM can read very low impedance loads with high accuracy. in the hands of a skilled technician, this can help sort out and detect wires which are suspect, with some broken internal leads, etc. At least use a DVM will at a minimum show go/no-go wires. (That's better than nothing, but a VTVM is superior, IMO.) Anyway, the condition of wrapped wires may influence your final decision about repair/replace. Do the electrical tests first and document any suspect circuits. Heavy/main wires deep in the harness rarely fail on a 66 harness that has not been abused. They sit there and never flex, so not much reason to fail if not overheated due to incorrect fuse values, etc.)
2. FOR ALL BROKEN/CUT WIRES - STRIP/CLEAN/SOLDER any repairs. DO NOT USE SCOTCH LOCKS, DO NOT USE WIRE NUTS, DO NOT USE CRIMP CONNECTORS. Solder / Shrink tubing for all connectors - no exceptions. A properly executed solder joint is as reliable as uncut wire. IF YOU DON'T KNOW HOW TO SOLDER - STOP HERE - Call AAW and order your harness. :-)
3. After generally cleaning the entire harness by wiping it down with solvent or strong cleaner, REWRAP the existing wrap to cover a small undamaged bare spots which do not look "factory". This is not nearly as hard as it sounds. You can untie the knot in the wrapping, usually found at the end of a harness lead, unwrap the covering (1" or 1 1/4" non-adhesive harness wrap) and wipe it down with a rag saturated with lacquer thinner. This will clean and soften the tape and restore it to a easily usable state. Works great, cost not much. Take pictures of the OEM knot and wrap first. This step will yield amazing cosmetic results if done right.
4. Using self-adhering harness tape, you can "repair" over top of a section where the OEM wrap is gone. This works well when there is actual break or cut in the OEM wrap that you can't "unwrap and cover". DO NOT USE CONVENTIONAL BLACK ELECTRICAL TAPE! (Did I say that already?)
5. Use OEM style non-adhesive harness wrap tape and rewrap an entire section or harness. This can become a lot of work, but it can be done. More advanced, but also gives great looking results when done right.
6. Remember that if you intend to replace the engine harness to accommodate an HEI or other non-points/coil setup, you'll need to do that work now - while you have things unwrapped. The resistor wire for the 66 ignition partly resides in your current wiring harness.
7. Whatever you do to the harness wrap, make sure to brighten and tighten all contacts in all connectors - including the fuse block. Phosphoric acid works great to brighten contacts, followed by a neutralizing bath of mild soda water. blow each contact dry with strong compressed air. NOTE: Phosphoric acid/Purple Power/ and other strong cleaners will remove the fuse designation paint from your fuse block - use caution there.
8. Clean and tighten fuse block fuse terminals. REPLACE ALL FUSES - EVEN IF THEY LOOK GOOD. GET THE CORRECT VALUE FUSES AND PUT THEM IN THE RIGHT HOLES. You'll be surprised how often these are the wrong values. USE MADE IN USA FUSES ONLY. Yes, you'll have to search to find them. Test and retain the "look good" fuses for spares. I write the value on the glass tube of the spare fuses with Sharpie - to make it easy. Then I put a complete set of spares in a sturdy little baggie and attach them near the fuse block along with a cheap LED miniature keychain flashlight in the baggie. You'll thank me later for that one.
9. Use a pick to tighten any loose female connectors. Carefully insert a dental pick from the back side of the connector body and "tighten" the slot by gently bending the free side of the female connector until the slot "closes up". (The "free side" is the side of the double folded contact which does NOT have the wire bonded to it.)
10. Connector repair: If only one or two plastic connectors on your harness are bad, you can contact AAW and they will sell you those plastic connector bodies empty (the blades of your OEM wiring just plug into the plastic connector body from the back side). Do your parts nomenclature homework first so you don't waste their time on the phone. AAW folks are super nice - so don't wear them out with ignorance. :-) After taking a photograph to document wire locations, release the contacts from the melted plastic part (it is very easy - practice on an unwanted bit of harness using a small thin pick or tiny flat blade screwdriver - Google it...) Then slip the contacts out of the old plastic housing and slip them into the replacement part. This is common on ignition switches and blower switch assemblies on the 66. VERIFY correct wiring location from that picture you took...or you will be sorry.
11. After cleaning and repairing, and right before installation, treat all contacts with contact enhancer. I use Caig contact enhancing products. (Google it). NOTE: DO NOT SCRATCH OR USE ABRASIVE ON THE CONTACT SURFACE! These are steel contacts coated with tin. If you scratch off the tin coating, the exposed steel will eventually corrode, causing failure.
Sound like a lot of work? It can be...but you can freshen an average dash harness in a few hours to a very good condition. Getting a good replacement dash harness costs something over $450.00 to get it in your hands. Do the math on the value of your time and your level of expertise.
...or, you could just buy a new AAW harness. They really are top notch pieces. I've gone both ways, depending on the harness. A common scheme is to replace the engine sub-harnesses and keep the dash harness. I've never regretted using an OEM harness that was worth using, and I've NEVER regretted replacing a questionable one with AAW parts.
Just my 2c