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so, Ive got a '73 project, and for whatever stupid reason, one of the PO's decided to ruin the wiring harness. Rather than trying to get a factory wiring harness, I've decided I want to go the route of a universal harness. i was thinking of going with a Painless wiring harness, which a few members have used, but the price tag scared me away. I then found the ez-wiring kit, 21 circuits, 18 fuses, all the wires all color coated and printed with the use of the wire... it's under $200 shipped. I'm thinking I'm going to go that route.. Been thinking about it and I know it will be a lot of work... But I can't see a reason not to go for it... thoughts?

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I have used the EZ wiring kit in a couple cars and it was nice. I prefer the mini panel that they make to the big GM style one and that's what I plan on using on my Z. The wire is very nice and fire resistant (I burned it to see) and with the mini panel I like that you can move the flashers/relay to a different spot.


I have used other brands as well and the extra cost doesn't really get you much. Ron Francis or Painless stuff seems the same quality as EZ Wiring but costs 2-3x more.


Forgot to add - the tech support is pretty good with EZ also. It's nice to be able to just call and ask questions.

Edited by Snailed
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+ 1 ^^^


I put a 12 circuit unit in my Z and had it all wired in, with the help of a local Z friend, in just one weekend... For under $200, it was well worth it. I just need to go back thru it and hook up the heater unit.


I was planing on pulling the air con / heater unit out, and replacing it with a Vintage Air unit, but have not made it there yet... :)

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I used the EZ Mini-20 on my 73Z since I found it locally on CL for $100 bucks.

WAY too many extra wires for my application.


I found the wire quality itself to be just ok. The sheathing isn't as durable as the really good wire you can by comercially.


I think if I were to do it again I would just buy bulk aircraft type wire and build it all up from scratch.

This is basically what you have to do anyway with routing and terminating all the wires and trying to make their harness fit cleanly in your car.


The lengths are fixed from the fuse box outwards, so you have to route and trim / terminate at the far end.

Invariably there were do-overs for me and things that needed adjusting and so the perfectly planned layout got messy.


If you were to start with blank wire and terminate at the far and then route up to the fusebox it might be cleaner.


In the beginning I was very diligent with heat-shrink and perfect connections and then the hacking and do-overs began.

But it does all work perfectly, took a long weekend and is trouble free.


Except, like a DA I didn't put in headlight relays. You need headlight relays.

Run big power to the relay right close to the lights.


A big trick for me was carefully planning and implementing the rear stop, running and brake lights.

Get it done and you will have perfect wiring forever more.


Oh.. one last trick..

I left a bunch of extra ground wires and some power wires in various places capped off for future use. (Fuel cell? Pump, gauges, cooling fans).

Leave these tucked cleanly away and next year when you add something you will LOVE yourself for already having a pre-terminated Power and Ground ready to plug into. I already had spade terminals on them and everything. Used 2 of them already for a wideband behind the panel and a knock sensor on the block.


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  • 2 years later...

Wow I made this a long time ago.  Well since October of 2011 when I made this I have gotten quite a bit farther along with my project.  At this point I have all the suspension in, as well as the engine.  Just today I started getting more serious about the wiring.  I went with the EZ-21 kit with a normal sized box.  It is way too many wires honestly, but at least I'll have plenty of extras for other additions, you never know what I'll want to add in later on.  Anyways I've now got the wires seperated out as to what goes where, and have just been trying to figure out a couple things.  I already wrote out my questions in a facebook datsun group, so I'll just copy and paste here:  I was wondering where I actually connect the main battery + cable to the harness? Or does the battery + only connect to the alternator, and then the wiring from the alternator connects to the harness? I apologize if that's a bit of a dumb question but I'm trying to figure out the wiring thing as I have never re-wired anything in a car so this is proving to be a steep learning curve. Other than that, I'm trying to figure out how to do the headlights and ignition switch. I am considering putting a universal headlight switch in, so that may be figured out. As far as the ignition goes, I have "IGN Switch ACC", "IGN Switch Power" (which is spliced to come out as two wires), "IGN Switch Start", "IGN switch IGN" and "IGN Switch Coil" on the harness, and "R", "IG", "A", "S", and "B" on the switch. Obviously, the "IGN Start" goes to "S", the IGN ACC" goes to "A", and the "IGN switch IGN" goes to the "IG", but what do I do with "IGN Coil" and the two "IGN Power" wires? I'm assuming that I only need one IGN Power wire, and that goes on either the B or the R and the coil goes to the other one, but which goes to which? Appreciate any help, thanks!

As I said, this is my very fist venture into car electronics, so hopefully I can figure out this harness without too much trouble.  I have already bought shrink tubing, electrical tape, etc.  I'm waiting on a soldering iron and crimping tool in the mail, and I will go out and buy some un-insulated terminals and some extra wiring from an electronics store soon, but I should be able to get this all going soon enough. 

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"I think if I were to do it again I would just buy bulk aircraft type wire and build it all up from scratch."

Did that with aircraft ceramic circuit breakers (not FAA Approved or it would have been HUGELY more expensive).... Nice TEFZEL aircraft wire. 


I missed having access to the Wire Numbering Machine in the Phase Hangar...


(For that matter, having access to NSN procured milspec aircraft wire, gratis...)

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Thanks for the replies, I think I've got the ignition almost figured out with the help of 5thgen's post.  I don't have the piggyback for the ignition switch, and was planning on just running spade terminals onto the terminals on the switch.  I'm now thinking about just buying a piggyback and going from there.  I also decided to get rid of the stock combo switches. I ordered a universal turn signal switch, a floor mounted dimmer switch like those from an old GM car, and a heavy duty toggle switch to turn the headlights on and off.  I have yet to think over the wiper set up, so that may be tough.  I'm still trying to figure out where the battery actually makes its way into the harness, but I'm sure that will be more clear when I start wiring in the engine bay.  Anyways I'm starting to get my head wrapped around the wiring so it's beginning to all make some sense. 

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  • 2 weeks later...
  • 1 year later...



On your wiper pdf, I only see 1 ez wire number going to the wiper assembly? #7 blue wire which is called wiper power. I see nothing for the wiper switch itself? besides you listing multi colored wire which the EZ kit does not have any multi colored wire? 


Does anyone have any idea how to wire the switch up for the 2 speeds? I bought the ez-wire 12 mini kit. I cannot find anywhere in my kit wires that belong to wiper besides the #7 wiper power wire.

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the wiper motor has a different lead for each the low and high speeds.  I used a 3 position rocker switch for my wipers (high/off/low).  the power goes to the switch and then from either high or low position to the appropriate wiper wire.  and, naturally from the wiper there is a ground wire.  see a posting I made last year asking which wire on the motor was which.  there were several excellent replies.  I only used the high and low speed wires.

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I painstakingly just finished installing and testing a painless 14 hole generic hot-rod harness in my 78Z/250GTO.I too was new to auto electrics.I can only say work slow, read directions many times.. I installed a vintage' heater only' and the Painless light, wiper, and ignition switches w/ the floor high beam and the OEM turn signal switch. The painless kit does not include grounds, so I ran three ground trees one between the headlights.one inside the rear tail lights and one under the dash from door to door.All exterior or weathered connections I used marine grade shrink-wrap (harbor-freight).I moved the battery inside the drivers rear fender ahead of the antenna.and modified the plastic inner cover to hide it from view and battery posts only on the firewall.  To me the unschooled this was a slow painfull job but in the end       " to my suprise "   it all worked    JIM

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  • 3 weeks later...

I had this same problem and finally just mounted it on the transmission tunnel just under the dash.  That way it was centered and easy to get to.  However I sold the original dash and made my own custom dash which made it a lot easier to route wires and figure out what wire goes where.  trying to figure out someone else's wiring (like the original Datsun wiring diagram) and adapt it is much harder than starting from scratch and doing your own basic system.

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