Ye olde wiring harness? When to replace?

Electrical and Ignition

  1. MRGTX

    MRGTX Well-Known Member

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    How many of you guys are running the original wiring harness in your cars?

    Mine is fully intact and aside from a non functioning fuel gauge (probably the sending unit as others seem to experience) everything worked last I tried. That said, some of the wiring is looking brittle, as you might expect from a 41 year old vehicle.

    How do you know when to replace the harness? I assume you shouldn't wait for a failure (as this might come in the form of a fire...no?)

    Is it as big/frustrating job as it seems it might be?

    Thanks for any insight!
    -Mike
     
  2. stansblue72

    stansblue72 one of one 1953 ME! Legendary Member

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    I replaced mine with a 20 fuse EZ wire harness. The job went pretty good, the biggest obstical was the plugs and connectors. The harness I bought didn't come with new ones so I ended up using most of the old one after I figured out how to rebuild them to take the new wire. I didn't want to just solder the new wire to the old stuff.

    There are probaly better harnesses out there but for the price I was happy with this one.

    You can see some of what I did in my bulid thread listed below.
     
  3. MRGTX

    MRGTX Well-Known Member

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    That's encouraging! I will check out your thread.
     
  4. roccodart440

    roccodart440 Well-Known Member

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    When you are experiencing failure or have outgrown what it's capable of.

    I'd stay away from painless.
     
  5. MRGTX

    MRGTX Well-Known Member

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    Haha... ok... Painless is no good? Is there a preferred aftermarket brand?
     
  6. CudaChris67

    CudaChris67 Well-Known Member

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    for a simple stock replacement, I would consider a factory style replacement harness intead of the headache of a "custom" type. Year one has them, Ron Francis has one, http://www.ronfrancis.com/prodinfo.asp?number=WR-95

    Usually when people are doing the more custom harnesses it is to both replace the old and accommodate electrical upgrades (power windows, fans, ac in non ac car etc)

    That said my car is more of a resto-mod/streetrod/pro tour with upgrades, battery relo etc so I will be using a custom kit:
    http://www.ronfrancis.com/prodinfo.asp?number=AC-68


    My brother's slant 6 duster mostly stock is getting the drop in factory style harness.

    also if you do a search for wiring harness you will find several threads with the good bad and ugly discussions of all of the major wiring harness manufactures.
     
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    • abodyjoe

      abodyjoe Well-Known Member

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      • gilberttitan08

        gilberttitan08 Mexican Hillbilly!!!

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        I reused mine. I checked the wires and made sure they weren't too brittle or deteriorated. If you can, use what you have.
         
      • 67Dart273

        67Dart273 FABO Gold Member FABO Gold Member

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        Make some actual tests

        Wait until it quits on the roadside?

        Wait until smoke appears?

        Read this MAD article:

        http://www.madelectrical.com/electricaltech/amp-gauges.shtml

        "It still works" might not be the best judge.

        And of course, ya never know, maybe it does. But frankly that might be unlikely. Some "voltage drop" tests which look for

        overcharging at the battery

        under voltage at ignition

        under voltage at headlights

        would be something you can do, even with no experience, in less than 1/2 hour, which would give you an idea

        The biggest list of problems with these cars is:

        Problems with the bulkhead connector

        Poor connections at ANY connector, top of the list is bulkhead, headlight switch, ignition switch, headlights themselves

        Ammeter connections and problems with the ammeter itself

        Poor connections in the fuse panel, both wire connections and fuse clips

        Socket connections at lamps, park, tail, head

        Rare, but sometimes failure of the "in harness splice"


        The instrument cluster "as a whole" has it's own set

        Broken / loose PC board connector pins, and or corrosion in the harness connector

        loose stud nuts on the gauges

        gauges out of cal

        bad / out of cal voltage limiter

        bad connections at the voltage limiter socket
         
      • roccodart440

        roccodart440 Well-Known Member

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        I'm not going to say they are no good. Their quality is fine.

        The issue I had is that if you don't use all of their parts it isn't so painless.

        I'd go with ROn Francis who makes didicated harnesses for our cars. Never heard anything bad about him.
         
      • BillGrissom

        BillGrissom Well-Known Member

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        In the engine bay of my 64 & 65 A's, I made a custom wiring harnesses w/ a modern relay box. The reason was both that the factory wires were brittle and I added provisions for EFI, fan, etc.

        In the cabin, I re-worked the harnesses - repaired cobbled & burnt wires, cleaned all terminals. Most cabin wiring I have seen is still fine, other than damage from short circuits and clueless owners.
         
      • blue missile

        blue missile Well-Known Member

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        Its time to replace the wiring harness when you turn on the radio and the windshield wipers start up! :glasses7:
        Andrew
         
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        • 67Dart273

          67Dart273 FABO Gold Member FABO Gold Member

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          The big issue I have with the "universal" harnesses like Painless, regardless of brand, but specific to my experience with Painless is...........

          I don't care for the wire labeling. Colors is fine, so is wire numbers. But Painless insists on labeling them "power windows," etc, which might NOT be what I use them for

          No diagram............Painless needs to print an actual diagram of their harness, mainly, so you know what the interconnects in the fuse panel, which also holds flashers, and horn relay, "is."

          Better Mopar support. This is easy. Just "mention" the "IGN2" path for the ign switch, and provide some real life docs for "what we do."

          I still haven't figured out if using a GM column connector is a good idea or not.

          UPDATE their blasted manuals. Since these are often pdf, there's no reason that corrections and updates can't be incorporated. I should not have to "call their tech line" for a routine wiring question

          (Holley EFI is particularly guilty of this. On my TBI Commander - to - HP upgrade, I could find NO where in the manual how to tell the primary from the secondary TBI injector connectors.

          Hell the tech guy didn't even have to look it up.........which tells me they get asked this.........a lot.)
           
        • airgrabber

          airgrabber Well-Known Member

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          Original harnesses here. Biggest source of problems are at the firewall connectors. Keep them cleaned and greased and you're good to go. I'd change them when the insulation gets brittle or the wires are too stiff to flex. Under the dash - that could be in another 20 years, under the hood is another story.
           
        • magnumdust

          magnumdust Well-Known Member

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          I did my car with Ron Francis. I wont be doing another car with their harness.

          I used this kit:
          http://www.ronfrancis.com/prodinfo.asp?number=XP-68

          The instructions were crap because very little of it was specific to a mopar application. Most of the instructions were specific to GM which made for a lot of google research to connect things properly.

          If you get down to it, the only thing that made it a "mopar kit" is that it came with a mopar electronic ignition harness
           
        • JoesEdge

          JoesEdge Well-Known Member

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          Like the original poster, I have wiring issues as well.

          There's all sorts of wires hanging down from under the dash, such as flashers and stuff. My turn signals don't work, and there's a short somewhere so I have to keep disconnecting the battery.

          Anyway, I'm looking to replacing my wire harness with something that is a "no brainer" so I'm very interested in this thread.

          So who makes the best, updated drop-in replacement wire harness? So far, it looks like the options are:

          1. Year One (can't find the complete harness on their site, any help?)
          2. Painless
          3. Ron Francis
          4. American Auto Wire (Note: A Body cars not listed on website)

          Any others?

          Oh, and excuse me if I'm stepping on his thread but maybe we have the same goals.
           
        • airgrabber

          airgrabber Well-Known Member

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          A short somewhere would mean you'd be either burning up wires or continually popping fuses. Now a drain, where the battery continually runs down, could be anything from the alternator not charging due to corroded connectors at the firewall, bad grounds to the voltage regulator, bad alternator, loose belt, or some component staying hot with juice when the key is off, like a radio, clock, trunk light, etc. A factory clock will, given enough time. run a battery down.
          Turn signals could be a bad switch in the column, bad flashers, bad grounds from the dash/firewall to the engine, the turn signal lights not properly grounded/bad grounds at the bulb sockets, etc.
          If you have the money you can buy all new, but if you want a challenge and can troubleshoot, get a FSM, the wiring diagram, a volt/ohm meter and start testing.
           
        • JoesEdge

          JoesEdge Well-Known Member

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          Thanks for the tip! I should not the hazards do work. I did wonder about the trunk light since I do have one, and it does work. So maybe it's staying on. Or maybe not. I don't know. I'll have to figure out a way to check. But, all the nasty "extra" wires and butt splices every where just looks plain ugly.
           
        • 64ragtop

          64ragtop Well-Known Member

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          Not to mention that those butt splices likely were improperly installed and they're UGLY. I'd say that the easiest fix is a new replacement harness from Year One. Their Mopar stuff is made by M&H in Cali and in my humble opinion, just can't be beat. It's not the cheap way, but they have all the proper plugs and connectors and the wire lengths are correct. That saves a LOT of aggravation!

          I learned in the construction industry that there are three desirable outcomes in any job. You want cheap, quick, & good. But you can only have two of those! If it's cheap and quick, it WON'T be good. If it's good and quick, it WON'T be cheap - etc, etc....

          BC
           
        • jos51700

          jos51700 Green Bearing thread connoisseur

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          I went with original, but I bypassed the bulkhead connector since that's where the problems arise. Grease it, use relays for accessories, and a battery disconnect never kept me up at night.
           
        • Inspector71

          Inspector71 Well-Known Member

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          Classic industries' harnesses?
           
        • Viper21700

          Viper21700 Well-Known Member

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          Ive got a possible interesting solution. Ive been reading about the issues and the problems with the early mopars all stem from underfusing, and bad connections. My idea is why don't you just take the problem out of the equation, while keeping the factory internal wiring, just lowering the load. IE- find a fuse/relay underhood block out of a mid 90's model Cherokee (dime a dozen at the local pick-n-pull) run your prime power into the block, relay everything that pulls a serious load (starter, blower motor, headlights etc) through the block. use the built in fuses for the interior accessories which all tie into the factory bulkhead connector. Seems like although not an original part, would remedy much of the trouble with the system, keep the install tidy, and wouldn't be too difficult to do. just a possible idea. Heck the more components in your system that are fused properly the better right?
           
        • 67Dart273

          67Dart273 FABO Gold Member FABO Gold Member

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          Some of us have done exactly that, but the problem "is not that simple."

          FIRST you have to fix the ammeter problem. Even Ma knew this was a weak point, ya want proof?

          Google up what is known as "fleet wiring." On the cars with 65? A factory optional alternators, Ma did an improvement in the wiring, running the ammeter wires through separate grommets in the bulkhead. That right there solves a bunch of the problem, because the tiny bulkhead connector terminals were NEVER designed to carry upwards of 40-50A, and now that they are 40 some years old, even the ignition / headlight circuits give trouble.

          I don't use a factory harness anymore, but I DO have a Voyager fuse / relay panel under the hood to run some of the loads, including headlights.

          So what you have as a solution is not exactly new It IS a good way to go.

          But the rest of the problem is, "if you leave" the factory harness there and simply try and improve it, you STILL have poor connections in the original fuse panel and at other connectors in the harness. This of course varies from car - to car.
           
        • adriver

          adriver Blazing Apostle

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        • krazykuda

          krazykuda Well-Known Member FABO Gold Member How-To Section Editor

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          The rule of thumb is the same with all electronics:

          How much smoke got out of them?


          You see, electronics run on smoke. It is inside them. The electrons transfer the smoke throughout the component and that's what makes if function. If you let out too much smoke from the electronic component, then it won't work anymore. It's like blood, if you loose too much, you die. Same with electronics & wiring, if you let all of the smoke out of them, they die....
           
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