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Which New Wiring Harness?

Discussion in 'Intermediate CJ-5/6/7/8' started by 72Greg, Jan 20, 2019.

  1. Jan 20, 2019
    72Greg

    72Greg New Member

    Loudon NH
    Joined:
    Sep 4, 2017
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    10
    My original wiring harness out of my 72 was completely hacked to death! I have been researching replacement wiring harnesses and I'm thinking of going with the E-Z harness after reading a previous thread on painless vs EZ. The main question I have is how many circuits should I get?? I have no AC, Radio, or power anything. I have the standard 4.2 258 L6. Any help is greatly appreciated!!
     
  2. Jan 20, 2019
    rusty

    rusty Well-Known Member

    norfolk,va
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    Dec 16, 2006
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    1,652
    Painless is very good, just expensive. I used Painless in my 75. The next build was a 79 and I used E-Z wire. When I build another I will use E-Z . I think I used the 12 circuit. Just tuck un used wires away in case you ever need them down the road.
     
    ojgrsoi likes this.
  3. Jan 20, 2019
    mike starck

    mike starck Member

    salem,oregon
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    Jun 22, 2006
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    762
    Ditto here 12 circuit mini fuse EZ no problems
     
  4. Jan 20, 2019
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
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    This story comes up a lot, and every time I see it I wonder "why?" It's got to be a psychological thing of being overwhelmed by the hacked up wiring. But using the original harness can't be any more complicated than fitting an entirely new harness, and adapting that harness to the existing devices.

    I would remove the harness carefully and repair it. Not that difficult. The '72 CJ has a fairly simple harness which is depicted graphically in the TSM. Very si9milar to the '73 or '74 harness, if you'd like to see the diagram in a different (schematic) format. I predict repair will be much easier than installing a new harness, and certainly less expensive. If you decide to repair it, this article may help you - ECJ5 Good experience, and it will match the original wiring for the Jeep. If you want to add more circuits, use a separate fuse panel - but you should only need this if you want to add accessories that require their own circuits. The original harness has all the circuits you need for a fully functional 1972 CJ-5.
     
    Last edited: Jan 20, 2019
    dane71 and ojgrsoi like this.
  5. Jan 20, 2019
    Howard Eisenhauer

    Howard Eisenhauer Administrator Staff Member

    Tantallon, Nova...
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    Nov 22, 2003
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    You're correct on the simplicity part Tim, stock harnesses work well & extra circuits are not that hard to add. But I'd point out that 50 year wiring with dried out stiffened insulation can be a 8!*@# to work with, and that's not taking into account where the PO's opened them up & the wire itself has corroded. There's also the issue of alternator installations- stock wiring was built to handle 35 amps, a 50 Amp+ alternator & more/brighter lights can roast the stock cabling.

    I myself went with a stock replacement harness, not the first vehicle I've done that on & I do not regret the money at all.

    The EZ harness will be a lot of work but at the end of the day you have fresh wires that will be good for another 40-50 years. :)
     
  6. Jan 20, 2019
    72Greg

    72Greg New Member

    Loudon NH
    Joined:
    Sep 4, 2017
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    I would love to be able to use the majority of the original harness and it is a VERY simple system. However, I have never seen such a wiring disaster in my life to the point where I have speaker wire all over the place. There aren't any speakers or a radio!! I'm going to do what I can with the old harness as far as pigtails and connections but to just repair what I have would, at the very least, leave me feeling uneasy. I counted that there are 22 different wires in the original wiring diagram. I have at least 45 to 50 going god knows where:confused:. That's why I'm looking to go with a replacement harness. I can't see paying Painless price (nothing against their product) I just wanted to make sure I didnt WAY over buy and get stuck with tons of extra wires. Just looking to do a total stock rebuild (this time):)
     
  7. Jan 20, 2019
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
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    I have found that the main problem with old wiring is oxidation, not the insulation. A '72 harness was made with automotive primary wire and uses PVC (poly vinyl chloride) insulation, a very durable and long-lasting plastic. PVC will embrittle with UV (sunlight) exposure, but under the dash or under the hood or under the car it will last a long time. This plastic is quite durable compared to the cloth-covered wires where the cloth protects an underlying rubber layer. The cloth-covered stuff seems to deteriorate badly, and I expect modern same-appearance wire is actually PVC underneath cloth. The '70s era PVC wire seems to be durable enough if not disturbed.

    Two aspects of this old PVC wire are problematic - first, the copper conductors tend to oxidize on their surface (especially near where the wire is cut), which likely makes new crimp connections problematic. Second, the grounds oxidize. Re-seating old grounds should be no different from establishing new grounds with new wire. It's the ground connection that's the problem, not the harness.

    You can deal with old wire if you solder using plenty of added flux. You need quality materials and proper technique. If the wire is not shiny-new copper, you need to solder and use extra flux. You can see whether your joint is good by how the solder flows. Get high-quality tin-lead solder, either a 63-37 eutectic mix or 60-40 (I like Kester) and a quality non-corrosive paste flux. Be liberal with the flux.
     
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  8. Jan 20, 2019
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
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    There's not that much to a '72 harness. The harness is continuous from under the dash through the firewall and to the engine. I encourage you to remove it all intact, lay it out and look at it. You may decide to remove all that extraneous speaker wire and fix up the original harness. Just remove all the goofy additions and make it like the original harness.
     
  9. Jan 21, 2019
    72Greg

    72Greg New Member

    Loudon NH
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    Sep 4, 2017
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    I will lay it all out and take a look. With the diagram and some zip ties maybe I can isolate the good from the garbage. Thank you for the input(y)
     
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