Wire size???

[cbudvet]

I would like to work on rebuilding my wiring harness over the winter months as a good indoor project. The problem is, I don't know what size of wire to get? Does anyone know what gauge wire is used for the 240z? Also, any good places to order a spool of wire. Thanks aplenty.

carl

[geezer]

You will want to replace each individual wire with one suitable for that particular circuit. The most common electrical problems we have with our Zs, are the corrosion and the resulting high resistance, causing heat damage. If you are going through the trouble to replace the wiring, some preliminary research is in order. Each individual circuit will have a different amperage draw depending on the device being powered, the length of wire used, number of connectors, etc. This all has to be considered before you can just replace the wire. This could result in the need for several different gauges of wire being used. If for example your headlight circuit has been upgraded with relays, a smaller gauged wire could be used for the control side of the circuit because it only takes .25A to control the relay. If you search the net you will find charts that show the calculated resistance of various lengths of different gauge wire. If you can't find it, I have it here somewhere. Do some reading on SAE wire specs and the temperature ratings as well as chemical resistance. In short, you don't want to cheap out on wire and each circuit is designed for its specific use. You can look at each original circuit and study it to find out what it needs to be improved. It just is not as simple as your question makes it seem, but don't let that scare you. It sounds like a great winter project. If you need help with anything specific, just throw it out here. One of us will have an answer.

[Zs-ondabrain]

I tore into a 7/70' engine harness a while back and measured every wire, and noted the length, color, guage, type of terminal (Male/Female/ring/bullet etc) and what type of connector (plastic) that it goes into and it's location on said plug.

It's written in a form that I can understand so here's a few clues..

LM6P is a Large Male 4 pin plastic connector which has male terminals

FQD is a Female Quick Disconnect (opposite of a Male terminal)

FB is a Female Bullet (open socket for a male bullet shaped terminal)

MB is a Male Bullet (this and above are used on sidemarkers, condensors etc)

You get the idea. Use it for wire gauges, lengths, whatever you want.

Good luck,

Dave

7 of 70 engine harness wiring.doc

plugs for harness (Small).bmp

[cbudvet]

Crap! I guess I thought it was only going to be a matter of grabbing some wire and soldering on some new connectors. I never thought it would be that complicated. Thanks Ron for your input. I may be checking back with you. I have a bunch of manuals that I need to get back from the body shop guy and will have a look. It may be more than I am up too! Thanks again.

carl

[Zs-ondabrain]

Also,

Check with http://www.crc2onlinecatalog.com/Index_Main_Frame.htm for terminals and connectors. If you call, ask for Teresa, she's great to work with but have your part numbers, quantity, and prices handy. It's helps her do her job better and will speed up the process.

I also use http://vintageconnections.com/mail_order_form.htm They are great for the 3, 6, and 9 pin connectors under the steering column cover.

Dave

[cbudvet]

Wow! Just as I was getting bummed out! Thanks Dave! That is awsome. That will save me a lot of work. This may just work out afterall. Gee whiz Ron, you had me scared but Dave has done all the work! I do appreciate all the help. All joking aside, I guess I have realized its not as simple as I thought. Its a lot more than a bunch of wire and terminals. As always, everyone here has my utmost respect and gratitude for the previous and future help you provide.

carl

[Zs-ondabrain]

Save the links to your FAVORITES list on your computer. Also Save the diagrams and stuff or just print them out for use in the garage or where ever you do your best work

Dave

[geezer]

HaHa, I scared you? Well I really wasn't trying to, just giving you an indication of what has to be considered, or else you are wasting your time. You did say "rebuilding my wiring harness'', which is not quite as daunting as recreating or duplicating. I have had a lot of experience doing this in the past and I can give you a few pointers that will make it a little easier. First thing you need to do is create a layout board, that you can string your existing harness on, make notes, take pics, anything that helps you maintain the original configuration so that everything is in the proper place on reassembly. You don't want to end up with a lead that is too short to make the connection or worse yet, entirely in the wrong location. A sheet of drywall is great for this and you can write on it as well. Also the white is a great background for pics.

When you do unwrap the individual harnesses, make note of how they are wound. Ideally you will start and finish your windings the same way. After unwrapping, it is best to use just enough masking tape or zip ties, to hold all the wires in their original position in the harness, yet allow you to inspect, measure, log notes, etc. This just makes it much easier to test, repair or replace each individual circuit. Hope this encourages you to go ahead with the project. Take some time to study the original connectors too. You need to learn how to work with these as well and should make a small investment in a few hand tools as well, that will last you a lifetime.

Edited January 13, 2010 by geezer

[geezer]

Carl, you need a method of quick reference and identification to keep track of all the connectors and their function in the big picture. Here is my suggestion for doing so. It is the easiest system I know of to follow. There are others. Most connectors are very easy to make drawings of. Each connector (which in this system includes both male & female ends) should be assigned an ID number and portrayed in the drawing as a mirror image, whenever possible. It could be a little more difficult to draw a mirror image when you have one connector, connected to an end device/accessory. In turn, all cavities in these connectors should be assigned a number, with both male & female ends sharing the same corresponding cavity numbers. The cavities that have a terminal & wire in them are called pin-outs. The pin-out information is then easily recorded, such as in the illustration below. In this example information box, it is not a mirror image, only the female side of the connector is shown and the end device is stated to be the "Power Distribution Center", but you get the idea. The ID number and color of the connector is shown. From left to right each occupied cavity is identified with a circuit number, wire gauge, color of wire, as well as the function. With a mirror image drawing there would need to be a separate information box for each the male & female connector end because of the tendency of wire colors or gauges changing, or the splicing in of a branch wire at the connector, etc.

You can tack each of these connector drawings complete with the information boxes on the layout board, alongside of each actual connector. This puts the harness, connectors and all relevant information all in one handy-dandy location. You can repair, redesign, solder, replace wire or connectors, supply power, test, etc. all on the board, right up to completion. This is a similar method to what we used to use to retrofit or redesign harnesses to include new features destined for the following years models.

This same layout board system could also be set up as a build jig, if someone had the mind to mass produce harnesses. Problem with that idea is the large number of variations in our Zs wiring harnesses, which would complicate the process substantially.

I hope I explained this in a manner that is understood and it is just a suggestion for devising a system that works and makes sense of it all.

Edited January 13, 2010 by geezer
spelling corrected

[cbudvet]

Ron,

I have a medical background (veterinary ophthalmology) and never had to take anything beyond the normal math classes so resistances and amps and all of that stuff is a foreign language to me. I had no idea that there was so much to wiring and electrical things. I assume its magic that lets my tv and toaster run. I really appreciate your help because that is what is going to keep me from half assing the job and burning up the car. Because I haven't found new wire with all of the original colors, I was going to make labels for each wire as to the original color to help keep track of them. Your suggestions make more sense and will let you know if I decide to tackle the job. Fortunately I have 2 wiring harnesses so if I mess one up I have a backup. I'll keep you posted!

carl

[geezer]

Carl, I just noticed at the bottom of this page, the "Similar Thread", when back in May you were first contemplating doing this. I would like to give you some practical advise, that I believe any one of us would benefit from. It would make much more sense to simply repair any damaged wiring while going over your entire harness. Unless a connector is damaged and the terminals will not remain locked in, why replace them. Terminals can be looked at carefully for signs of corrosion and cleaned or replaced if nessesary. Look for deadheads, broken strands, corrosion traveling under the insulation, burned wires, etc. Point is, only replace what is nessesary. It would be nice to build a new harness with all new wire, but not really worth the time and expense to do it properly. Take advantage of products already available such as Dave's headlight relays, to eliminate the high amperage destructive heat. Proven winners that will save your wiring and switches. Keeping all grounds and connections free of corrosion is the single most important thing you could do on your own. Also, as part of the hobby, if you are serious about getting to know your cars electrical systems better, try studying the circuits in your car. By following a single circuit in a wiring diagram, you can draw it out separately with all components shown on a piece of paper and gain detailed knowledge of how everything works. Learn the actual location of these components and the routing used in the car. It is not so complicated when broken down into separate circuits. Study one a week in your spare time and before long you will have the confidence and knowhow to troubleshoot any electrical problem that comes up.

I'm not saying you couldn't replace all the wiring, but it does entail much more than you realize and I think you would need more intimate knowledge of the electrical system. One of the most significant problems is one that you have already recognized. The shear expense of buying enough quality wire in the various colors as well as compounding that by the different gauges of wire needed would be enough to halt the project for me. Then add the cost of terminals and connectors. I once estimated what it would cost to reproduce a Z harness and came to the conclusion, no one would want to pay what I would have invested in it plus what I figured my time was worth. Maybe, if mass produced, they could be priced reasonably enough.

It's good that you have a spare harness. You can go over it on a layout board and test/repair as needed while learning at the same time, but I would advise against replacing all the wires, unless you really feel you are up to the task and prepared to spend a few bucks doing it right. You don't want to be referred to as the dumbass PO that used all red 18ga wire for the entire wiring harness.

[cbudvet]

Ha! Thats great! I've been known to be a dumbass about a lot of other things. I better just leave it, and not give people more excuses than necessary. I guess I never thought about leaving the harness alone. I know there have to be a lot of cars out there with just as, if not older wiring and they do just fine. I guess I thought that automatically having an old harness, replacing the whole thing would be important. I appreciate your input, as always.

carl