Building a wiring harness from scratch

[Grumblebuns]

I'm getting very close to starting work on my wiring harness for my TCS 3631R. The original harness is probably typical of most Europas, cut/spliced and modified by previous owners. It is marginally usable as is but I decided to construct a purpose built harness. I'm looking for feedback from others who have done this, primarily lessons learned and what you would do differently next time.

I'm still undecided if I will be using the British Standards wiring color code. British Wiring last time I checked had some of the colors and sizes but not all. Right now, I'm leaning towards non-Lucas wiring colors for flexibility and availability of product.

A lot of you will think I'm nuts going this route but I will be using the Infinitybox wiring system. Discount the initial cost, the advantages of streamlining the wiring process makes it worth the cost for me.

http://infinitybox.com/custom-wire-harness-markets/#aftermarket
http://shop.infinitybox.com/INFINITYWIRE-20-Circuit-Wiring-Harness-p/inf3boxz.htm

Joji Tokumoto
Fallbrook, Ca   

[RoddyMac]

I've built two harnesses from scratch and have modified my Europa harness (taken it right back to nothing, added circuits etc).  I'm very familiar with the Lucas wiring colours, so I've always used the same colours. If I didnt have enough of one type of wire I would use the basic colour and use a small amount of coloured heat shrink at the connector ends to match the colour code it was supposed to be (eg a green/white, would be a green wire with a small band of white at the connectors). 

There really isnt any magic in building a harness nor figuring out how it works.  Just lay things out, use zip ties to keep bundles together while building the harness, then when taping it up, remove them as you go.  I would suggest getting some of the non adhesive harness tape/wrap if you are wanting to tape the harness.  It makes things much nicer down the road if you need to "open up" the harness,  plus regular electrical tape doesn't stand up very well to heat and various fluids that a car contains/leaks/emits. 

As for a wiring diagram, I'd start with the Lotus one and work your way through it.  Most british cars from the same era are similar, so can also be used as a reference.  The harness I made up for the Eleven I built was made up using an MGA wiring diagram as reference.   

[jbcollier]

I used the standard British wiring colours as it makes trouble shooting easy ten or twenty years down the line.  This place is much better stocked with all the various wire colours and sizes:

http://www.autosparks.co.uk/index.php

Thin wall cable is the way to go.

[Clifton]

I had to add a fuse/relay box for the EFI/ fans, pumps ect on mine and used the box in this thread http://www.bodenzord.com/archives/473. The large box was around $45.  I used Weatherpack connectors on everything I did so I can remove the power box with the harnesses separate from the engine.

[HealeyBN7]

I used an EZ Wire kit as I had no real wiring to start with and I needed new circuits for the Zetec install and I wanted to move things around a bit to support an S1 dash.

If you can get to this pdf, I documented all the connections and circuits for the instruments, relays, sensors and running lights.  I decided to standardize on commonly available relays, so you will see I did something a little different for the wiper motor as an example.

The nice thing about the EZ Wire kit is all the wires are marked down the full length, so once you lay it out, you will know what you are looking at even if you can't see the other end.  Buy extra fuses...testing is sometimes trial and error as the EZ Wire fuse block assumes some circuits are "connected".

I wasn't concerned about originality.  For my other British cars, where originality matters, I stick with the standards and found that the wiring available from BW is adequate, yet not always 100% correct.

You can try this link for the .pdf.  It was deemed too large to attach .  I'll try to shrink it down.

 It was last updated in June of 2015 and is current to my Lotus.

https://groups.yahoo.com/neo/groups/lotuseuropa/files/Zetec%20S2%20Wiring%2C%20Fuel%20Injection%2C%20OMEX%20600%2C%20MegaJolt%20Manual/

Dean

[LotusJoe]

Uploaded your PDF

[HealeyBN7]

Thank you.  I could not figure out how to make it smaller!

[Grumblebuns]

After thinking it over last couple of days, I'm currently leaning towards going with the non British color code wiring. My situation is very similar to HealeyBN7, no harness to start with, running an alternative engine and ignition system and additional circuits.

As long as the wiring documentation is complete and accurate, the non standard colors won't be an issue. By using a universal harness, there is no need to buy individual rolls of wiring. HealeyBN7 has already done the grunt work with his system. I'm thinking of using a similar system.

Dean, what graphics system did you use to construct your wiring diagrams I'm very impressed with the simplicity and readability of the diagrams. Also if I have to use relays, Clifton thanks for the link.

Joji Tokumoto
Fallbrook, Ca       

[HealeyBN7]

That fancy graphics package was just me pounding away at Powerpoint between conference calls at work. Glad it will be helpful.  If you use the same Ez Wire kit I used, you won't even have to think about the colors... I was a little unsure about abandoning the BW standard, so I committed to documenting every circuit so I wouldn't be cursing me as a DPO.

Happy to send you the .ppt file if that will help.

Dean

[Grumblebuns]

Thanks Dean, I've downloaded your PDF file. I just need to figure out a way to modify it for my use.