E86 electrical question/view please

bigwinn

bigwinn

Elite
 Lincoln UK
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Forum collective hive mind- a view please

I have an E86 with electrical issues. Long story short I think it has had a combination of water ingress and fuse overload leading to pretty significant loom damage.

Also, add in the mix lots of previous attempts to fix.

Now, the simplest fix in my mind is replace the loom, a tedious job but doable.

I've found a loom, but the spec of the car is not like for like- donor car doesn't have xenons this one does. That's not going to work is it?

So I need to either:

1) Find a loom with the majority of similar components and functions

or

2) Repair the damaged sections, either using new wiring or donor sections from the donor loom

or

3) use the donor loom and rewire the missing loom components (like xenons)

Am I right in these assumptions?

What would you guys do?

Stuart
 
Tricky. I'd not fancy stripping the interior just for the sake of repairing a few wires. I think on a time/effort/cost basis, the repair would be the better option if you can find all of the damaged parts of the loom.

However, if all your donor loom is missing is xenons, then here are the PDF instructions on how to retrofit them, so you can get a good idea of what wiring would be involved (I assume it would just be the two levelling sensors, but I didn't really read it in detail to confirm)



Edit - looks like you've stripped it down/removed the carpet etc already. I'd probably still favour repairing the existing loom - unless you know for sure what state the new one is it? Was it or the plugs/connectors damaged during removal etc?
 
That’s very useful thank you

The plugs weren’t too damaged thankfully but my worry with the loom is that other wires surrounding it have been heat damaged too!

So far the old loom is I’d say 50% removed and everything is stripped.

So getting the loom on the ground and having a good inspection is probably next as it’s too hard to tell when it’s in the car still

Appreciate the reply- top man
 
Hi mate,
For a start that damage could only be caused by water ingress (causing shorting) or someone fitting higher than spec components (apparently it is the biggest cause of car fires). Or possibly vermin eating the insulation.

As said above if you are contemplating changing a complete wiring loom; think carefully. It is a mammoth job and would need meticulous planning and note-taking.

As for wiring looms themselves...I am 99% sure that all BMW cars of a particular model have exactly the same loom; there will be a myriad of 'spare' cables for different accessories, specs and market requirements.
The ONLY thing I noticed when virtually re-wiring a Z3 (which are 95% the same as an E85/6) is you need to make sure your ECU and all electronics are the same for both looms. That is where the looms change. I know because I was caught out by using a wiring diagram from a car which was a year older than mine. Mine has an updated, different, electronics system and a lot was different; which I didn't realise until it was too late.

Having done the above there is NO WAY I would even contemplate changing a complete loom in a modern(ish) car. There are too many ways to make a mistake and there are fecking cables everywhere.

Stripping and soldering individual cables is a LOT easier, even if there are multiples of them.
 
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Looking at the state of the loom I would want to inspect every inch of it out of the car, which would be a pain to do and time consuming, I think your best option would be to get another loom and then check every connector to see if there are any differences in the wiring and add any that are missing, I don’t think I’d even risk using any of the old loom, just replace with similar gauge and colour simply taped to the outside of the “new” loom.
 
If it were me, I'd remove the complete wiring loom out the car and lay it out on the garage floor or garden. It'll then be easy to work on.

As you know, the kbus is a series of wires all tapped together but I believe there is another group of wires which does similar. Without pulling my loom out and checking I can't be sure.

With the wiring laid out I'd then just replace the wires from another loom and then put the original back in the car.

You'll need to remove all the foot pedals but I think the air/blower/vent unit can stay in place. You need to unplug some wires from the engine bay but I can't guide on that as I just chopped them off.
 
Thanks all

The easier solution in my head was new loom- purely as I suspect kbus damage: there were modules that weren’t communicating at all which makes me think the kbus loop was fried in the original overheating wire

I hear both sides of the argument for new loom versus repair.

We haven’t looked yet at option 3 which is break the fecker as it’s 75% done already

However it’s a fairly low mileage car in manual format soooooo…..

Lots to ponder

I think @GenZed has an si loom I can pull apart to be a like for like donor with xenons so that a step forward!

Appreciate the input
 
I’m an electrician by trade, been at it for over 35 years, mostly working on some pretty serious machinery. One thing I know for sure is once wiring starts breaking down it never gets better — you’ll start getting backfeeds, random faults in places that don’t make sense, and it’ll drive you mad chasing them. If you’ve got the skill to swap the loom, I’d do it. Otherwise you’re just inviting gremlins into the system.
Click to expand...
 
finally got the loom out this morning- to be fair I’ve only been picking away at it

With the loom on the grass I can see how deep the damage is

I’m surprised the car didn’t catch fire

New loom incoming IMG_8850.jpegIMG_8852.jpegIMG_8854.jpeg
 
Having just stripped out and replaced my whole audio loom (which is approx 50% as complicated as what you have laid out on the lawn) it is not something I would ever want to do again. However, that loom of yours is fried. Which leaves two options only - replace completely, or scrap the car. Repair does not look like an option.
 
Yeah it’s done (the loom)

This is just one repair I have uncovered now it’s out the car

That’s not bodgery it’s criminal IMG_8858.jpeg
 
bigwinn said:
Yeah it’s done (the loom)

This is just one repair I have uncovered now it’s out the car

That’s not bodgery it’s criminal View attachment 283934
Click to expand...
And then people wonder why their cars catch fire.
I can only assume whoever did that thinks 'it's only 12 volts, what's the worse that can happen?'
Electrics are not something those who have no clue should ever get involved in. I have seen some scary household electrics in my time, all done by DIY enthusiasts without a clue.
 
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