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Author: Subject: Wiring Loom, Wire Rremoval
subjated

posted on 29/3/17 at 07:39 PM Reply With Quote
Wiring Loom, Wire Rremoval

Hi all, may sound like a silly question but im not totally sure so thought id ask...
im currently building an mx5 powered haynes roadster, and having taken the mass of wires that is the loom out of the donor, the spaghetti mess of wires is already giving me a headache, so i might start fiddling with it in my spare time ahead of schedule. but am i right in thinking that the wires that i dont need: radio, mirrors, windows, interior lights etc etc, i can remove from the loom by tracing single wire at a time to where it terminates and remove it from there?
any help much appreciate

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coozer

posted on 29/3/17 at 07:46 PM Reply With Quote
I started on the floor scratching me head then hung it on the garage wall, unwrapped all the gunk off the outside and used the manual to remove all the circuits I didn't need. I ended up moving the fuses into the top half of the box and cutting it in half!

Hanging it on the wall in 2d fashion with each corner resembling the car on its side worked wonders...

Once I'd laid into the MNR, trimmed them all back everything worked first time..





1972 V8 Jago

1980 Z750

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gremlin1234

posted on 29/3/17 at 07:57 PM Reply With Quote
I would leave the 'extra' wires in the loom only adds a few grams,
however if removing wires, you will then have to re-wrap the loom.
I don't know about the xm5 loom, but normally wires are colour coded, so don't need to be traced.

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chris_smith

posted on 29/3/17 at 09:21 PM Reply With Quote
I did mine several weeks ago,mx5 loom, take your time, my advice is to start and continue till finished or you end up getting lost trying to recall things,, make notes, don't just assume that because you aren't using a particular part i.e. Interior lights, that they don't feed something else. I measured out loom length required for particular location on the. At then transferred that to a board with straps to lay out the loom and made a new loom using the original one

Wiring diagrams

I found this link really useful as they seem to have differing colour wires for each year?





The secret of success is to know something nobody else knows."

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ianhurley20

posted on 29/3/17 at 09:56 PM Reply With Quote
Mine was an NB Mk 2 and was a pain. Take out the dimmer for dash lights and the ECU won't fire up - take out lots of wires and suddenly you find other things don't work - its a real pain and I took out all the electric windows, air con, radio wires to start and then took out anything I thought I didn't need, then came making wires the right length, that really took some time, mainly shortening but keep at it and eventually it will get there. The alternator on the NB is controlled by the ECU and the control wires take a very strange route, be careful not to lose those - guess how I know that one!!





My build blog http://ianhaynes20.wordpress.com IVA passed 3/10/16
written off 23/9/18
Aug 2019 completed Tiger Avon with ST170 on TB's
Now restoring 1968 Ginetta G4
And - a series 1 Land Rover - don't ask why!

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subjated

posted on 31/3/17 at 08:32 AM Reply With Quote
hi, thanks for all the replies....


quote:

I found this link really useful as they seem to have differing colour wires for each year?


this is a great info thank you


quote:

I would leave the 'extra' wires in the loom only adds a few grams,


i actually think its closer to a few kilos, and the amount of extra wires would take up quite a lot of room, hence why i didnt want to go down this route.


quote:

Mine was an NB Mk 2 and was a pain..... and the control wires take a very strange route


mine is also a mk2 and this is what worries me, but you say about removing certain things that control the ECU if you keep these wires in the loo you should be ok right? is this what you did in the end?

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ianhurley20

posted on 31/3/17 at 02:22 PM Reply With Quote
quote:

Mine was an NB Mk 2 and was a pain..... and the control wires take a very strange route


mine is also a mk2 and this is what worries me, but you say about removing certain things that control the ECU if you keep these wires in the loo you should be ok right? is this what you did in the end?



Yes that's right - I had other problems with the ECU which took me ages to diagnose. The MX5 ran fine but when the ECU was put into the roadster the corroded wires and track lost integrity and would not conduct so I spent ages chasing an elusive wiring fault. I started with all the wiring for the doors, then the radio and worked my way through the loom one thing at a time - but watch the dimmer switch as it returns a feed to the ecu which will stop the car and the alternator wires take a very strange route indeed. I found the wires for one side of the rear lights had to be extended but mostly it was a case of shortening lots of wires behind the dash. Take your time and do it bit at a time and it will work fine in the end





My build blog http://ianhaynes20.wordpress.com IVA passed 3/10/16
written off 23/9/18
Aug 2019 completed Tiger Avon with ST170 on TB's
Now restoring 1968 Ginetta G4
And - a series 1 Land Rover - don't ask why!

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Ianboom

posted on 13/4/17 at 08:10 AM Reply With Quote
I'm just finishing building a Westfield with an MX5 Mk2 donor.

I stripped all the unused circuits off the harness and fitted it to the car-I had to pass a load of connectors through the bulk head so ended up taking a lot of plugs apart to do it-fun!

I then shortened the harness so I have a really neat, tidy run.

The one thing I would do next time would be fit the harness to the car, get everything working and then start stripping the unused parts off! I did a lot of head scratching as I had some wires that didn't have a plug on the end and all the wiring diagrams I could find were for US or Jap spec cars.

I couldn't start the car when I fitted the harness, there were 2 wires, both green and red, but one was live on cranking, the other wasn't. I had them the wrong way round!

I have a complete MK2 harness going cheap if anybody wants it-I bought it with an ECU kit to help me fault find my car.

Ian

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kevyo89

posted on 3/3/19 at 10:17 PM Reply With Quote
Sorry that I'm reviving an old thread, but I'm about to start this painful process myself.

My only saving grace is that I have a complete loom and ecu from an MX5 and labelled all of the bits as it was taken from the donor.

I'd planned to lay it out over the car and connect it all up, then ensure it starts. From there, I planned to use the pinout diagram to remove what I didn't need, ensuring to frequently turn the ignition ove to make sure that I didn't remove something important.

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ianhurley20

posted on 4/3/19 at 08:29 AM Reply With Quote
quote:
Originally posted by kevyo89
Sorry that I'm reviving an old thread, but I'm about to start this painful process myself.

My only saving grace is that I have a complete loom and ecu from an MX5 and labelled all of the bits as it was taken from the donor.

I'd planned to lay it out over the car and connect it all up, then ensure it starts. From there, I planned to use the pinout diagram to remove what I didn't need, ensuring to frequently turn the ignition ove to make sure that I didn't remove something important.


That sounds like a good plan. I guess you have the ignition key that matches that ECU - its a PAT system (passive anti theft) they are matched. take it easy and do one bit at a time and it will be fine.





My build blog http://ianhaynes20.wordpress.com IVA passed 3/10/16
written off 23/9/18
Aug 2019 completed Tiger Avon with ST170 on TB's
Now restoring 1968 Ginetta G4
And - a series 1 Land Rover - don't ask why!

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Ianboom

posted on 4/3/19 at 09:43 AM Reply With Quote
That's a good plan.

I still have the spare harness, I was contemplating removing the unused wires out of it and selling it on as it has sat in the garage for nearly 2 years!

Ironically, I started the Westfield yesterday, I considered taxing it and taking it for a spin until I read this weeks weather forecast!!

Ian

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snowy2

posted on 10/3/19 at 07:42 AM Reply With Quote
generally speaking unless your using the ECU from the donor car its really not a good idea to reuse the donor loom. if you are using the ECU the wiring associated is generally easily removed from the car....
rewire the basic functios for your car from scratch ITS EASY and there is an article on here on how (How to wire your car the easy way)





sometimes you are the pigeon, most of the time the statue.

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