Which wiring harness?

Hey guys and gals. I have a 67 cougar and I’m looking to redo the wiring. I don’t want to use the stock harness cause I want to put ac, power windows and all that. I was looking at painless harness for the mustang but found other companies like American auto wire and streetrod electrics. I was wondering if anyone has any info about any of these companies? Painless is the most expensive but I’d have to modify the harness anyway so I’m not sure if it would be a benefit to the cheaper kits that aren’t vehicle specific

I hope someone chimes in who has done this as I too am interested in replacing the factory harness.

I am a true believer in the American Auto Wire harness. I did my first one on my Mach I and this second one on my 67 Cougar. I tied in the elec headlight motors and sequencial box also. I have all the wiring diagrams of exactly how I did everything.

67BOXCAT can you post up those pictures? How did you like American autowire? Easy to install? Do you have an electrical background? Just want to see what I’d be getting myself into. Like how the pink ignition wire worked out and stuff

In you 67 cougar did you get the factory fit mustang harness?

I am glad that 67boxcat chimed in. I think he is about the only successful conversion we have seen. It is possible and you should definitely learn from his experience.

Also how long did said conversion take?

Contact Randy Jacobson at Midlife Harness Restorations
850 248 1967

I used American Autowire as well. Really simple. I used the extra relay that the mustang used for fog lights control the headlight doors. I used a different sequential taillight setup, I believe from speedway motors, and a led flasher can. Very simple. I even changed my car to a xr7, added a low fuel light kit, changed all gauges to auto meter, and have idiot lights. Ac and power windows. All toggle switches are wired and work along with overhead console.

Don’t do it I say… The originals are designed for ac and adding PW is easy. Easy and inexpensive to find quality used original harnesses and nothing will work as well with our unique cars.

I’m with Don and Bob. Unless your car is missing all wiring and you want to add some unusual modifications, going with the basic stock configuration will save you money, time, and effort. Particularly years down the road: you already have the Shop Manual and schematics to trouble-shoot. These harnesses have lasted 50 years without that much degradation (except from previous owners butchering them) and with care can last another 50 years. Some harnesses are not worth restoring (e.g. alternator and engine gauge feed harnesses) but are readily available as reproductions.

I’ll even tell you to buy them from Don instead of me. Support your local vendors and craftsmen!

I would but I was cutting out all the extras the previous owner had and a lot of the wires are so old and corroded and all black. Couldnt even solder them so I figured I’d get a new harness since I want to do a remote power trunk, power windows, keyless entry, power door locks, small amp for new speakers, etc. I just wanted to keep it clean and get rid of the glass fuses.

Yes, it was easy to install since the entire car was apart. I will leave the rest up to you. Wiring an entire car is no small feat. I am sure I can post pictures but I installed it just like the original so you really cant tell. I am really impressed with the American Auto Wire “New Builder 19 Series Wiring Kit - 510006” I installed. The additional mods to the electrical system helped a lot too. Pertronix, Probe motor headlight doors and Sequential tail light kit, Elec Choke etc. My background is electrical and I enjoy figuring this stuff out. Whats the worse than can happen? Blown fuse? lol.

Im not going to apologize for this because its just my opinion/statement. I cannot bring myself to install any factory wiring on these old cars because I know the wires sizes they used seem small for the loads they ran on them. Also, Ever try bending or stripping 50 year wire insulation? Cracks can show up anytime and you will never see them until the smoke starts to come out of the wires. It works best if we keep the smoke in the wires. The last thing I ever want to do is spend a boat load of money and time on a build and then have the sucker burn down to the rims due to old wiring. Again, this is just my opinion.

No apology needed 67boxcat! We are going to have to figure this out for the future. A lot of desert cars have nice sheet metal and that is about all that is left the wiring is so hard the insulation just crumbles. My first choice would be a plug and play direct replacement for the factory harness, but that doesn’t exist, and won’t until originals get to be even more scarce.

I cannot bring myself to install any factory wiring on these old cars because I know the wires sizes they used seem small for the loads they ran on them. Also, Ever try bending or stripping 50 year wire insulation? Cracks can show up anytime and you will never see them until the smoke starts to come out of the wires.

If you want to see wiring that seems small for their loads, check out today’s vehicles: they use 24 gauge wire on 10 amp fuses, or so it appears. Car manufacturers can save weight by going to smaller wires (higher gauge size) and more circuits via fuses, and reduce their safety load factor from 2+ in the mid-60’s to 1.2.

As far as brittle wiring, some engine compartment wiring does get brittle for sure, but from what I’ve seen it’s about 10% of the harnesses that I see. For underdash and tail-harnesses, I almost never see brittle wiring, unless the harness has been exposed outside for several years. Obviously southwest cars (e.g. Arizona) are problematic. I’ve seen more shorted wiring than I have brittle insulation in the underdash/tail harnesses by far.

Working with the wire harness’s from these cars (67-73 and all harness’s) I have seen them at both ends of the scale. I have cleaned and repaired many of them and there are some things to be careful of and aware of, for instance the gauge of wire for the early 67 brake switch, almost all are melted or plugs distorted from heat. But for all of that many are still soft and pliable and in very good shape. By the way we never save any harness that has melted wires or shows distortion. I to love changing my car to suit me, as many know my 71 std has been converted to XR7, and done without changing the standard harness. All the extras have been added, door ajar, E brake light, tach, oil pressure gauge, left the amp light in the dash and added Rocketmans volt meter, elec trunk release (wired to the XR7 map light switch) XR7 switch panels, 8 track, 4 channel amp,remote cd player, power antenna using an original ford antenna with a full size merc switch, etc,etc. My point is almost anything can be added using the factory harness’s. For 67 your ac harness is a stand alone harness and was not part of the main underdash harness. There are plus and minus’s in anything and I think you should do whats comfortable for you, for me I like looking at the book and knowing the blue wire with a red stripe goes to an interior light!

Thanks to all of the more experienced for chiming in. I was wondering if anyone made a harness specifically for the early Cougar, and now I have my answer. Out of curiosity’s sake, I took a good look under the dash, and in various spots of my factory harness and wires and to my surprise they are in great shape. The only spots I could find on mine that were in need replacement were the gauge feed (which I replaced last week), and the alternator harness which I am replacing this weekend. It seems that the only wires with bad insulation were the ones exposed both to engine heat and the extreme cold from the Illinois winters. Luckily, nobody made any stupid cuts or half assed repairs since 1968.

A lot of good information. I may even just add extra junction boxes for the acc this way I retain the factory wiring that works and still have a clean appearance. I’m thinking about adding high amp items such as electric fans and all so it might be nice to have an engine jbox