Wire Harness Thinning Thread

[Nish90]

Originally Posted by roastbeef

anyone have a good lead on bmw tis wiring diagrams? all i'm finding is expensive paywalls and dead links.

What are you looking for, specifically? I have access to wiring diagrams I can try to find what you're looking for.

[roastbeef]

Originally Posted by Nish90

What are you looking for, specifically? I have access to wiring diagrams I can try to find what you're looking for.

Thanks for reaching out. I didn’t know what to expect, but I gained access and it just wasn’t what I hoped for.
It’s a bunch of electrical diagrams (duh) in an engineer’s schematic. I guess I was hoping for more pictures and a wire color key. It just wasn’t helpful for my knowledge level or how my brain works.

one of the things i'm hoping to achieve is dumbing this down for other people like me. as i'm getting started with the wiring, i'm realizing it is not that complicated, just complex. the community is very helpful as well, i posted on an instagram story asking about a cluster of 6-7 wires going into the driver's wheel well. couple people responded pretty quick stating which wires did what. the answers are all over the place and i'm hoping to make it less complicated for the weekend amateurs like myself.

[TheStevo1000]

Is this a relay for the radiator/engine fan? I assume you don't want to remove that...

I'm gutting my car right now, and I've been weighing nearly every piece I remove with an accurate shipping scale. If you're interested:
Complete HVAC system (heater core, blower, controls, wiring, vents, etc) - 23.5lbs
AC compressor, condenser, lines - 15lbs
All airbags, including control module - 11lbs
Bluetooth/telematics module, all antenna modules, full wiring harness for those - 14lbs

[amg6975]

Radiator fan relay, yes. Best to leave that one where it is.

[mikerunt]

Originally Posted by DRLane

I’d also note, given your sub 3k or bust goal spxxx the complete wire harness from end to end only weighs ~59 lbs.

I know this because I pulled and labeled the entire harness from my 08 e92 (with most of the options including sunroof, drive) except DCT. That’s from the rear taillights, through the firewall to headlights but not including the underside battery cable.

I sent this to Germany and the 24”x24”x24” box weighed in at 62lbs. Had Martyn from Project Rogue thin it down retaining only the driveline and light components necessary. Don’t have an updated weight but will share once I do.

This means a significant portion of the 40-50lb weight savings you see posted with harness thinning is the modules, plastic brackets, metal brackets, etc. It’s not just a jumble of wires…

https://youtube.com/shorts/i6jrddnxPKI?feature=shared

Did you send to Project Rogue?

[DRLane]

Originally Posted by mikerunt

Did you send to Project Rogue?

Yes.

[TheStevo1000]

Another question:

I'd like to get rid of this thing on the battery. I have a remote battery shutoff I will install. The battery power cables are obvious, but what about the 2 small connectors that are plugged into it? There's a single wire plug that goes to the negative terminal...Then a 2-wire plug that goes all the way to front into dash harness. Does anyone know what to do with those?

[roastbeef]

blue is associated with airbags, and i believe the other is the intelligent battery system primer that fires and disconnects the battery in the event of a crash.

[amg6975]

The blue is just the power for the IBS. The two other wires are wake up (R/G) and the control signal from the DME(Blk).

I think there was a pretty major revision to this system at some point, I'm guessing your car is an early car? And that's when the airbag fuse was added, which it doesn't look like you have. That would be a twisted pair going to the BST (big red thing.)

I have no idea what the DME will do if the IBS isn't there, I don't know if it can be coded or tuned out. I would leave it in place.

The next thing is the main purpose of the BST is the fuses. If you remove it you'll have no fuses on all those lines. One goes up to the starter, one goes to the JBBF, and one is for the radiator fan.

[turbo_joe]

Originally Posted by TheStevo1000

Another question:

I'd like to get rid of this thing on the battery. I have a remote battery shutoff I will install. The battery power cables are obvious, but what about the 2 small connectors that are plugged into it? There's a single wire plug that goes to the negative terminal...Then a 2-wire plug that goes all the way to front into dash harness. Does anyone know what to do with those?

I remove this entire unit to install my kill switch. Ditched the extra wiring and its never been an issue. I rain my main power from the battery to my kill switch. Kill switch feeds a fused distribution block. The block feeds the DME, Alt, fan, and an aux switch system I have for a handful of things (helmet fan, rear view cam, diff cooler pump/fan, etc.)

Side note: I run a small lithium battery, not the oem battery

[omgzirra_exe]

Originally Posted by amg6975

I have no idea what the DME will do if the IBS isn't there, I don't know if it can be coded or tuned out. I would leave it in place.

certain e9X didn't come with IBS from my understanding, but from my own experience when its not plugged in it was never a good thing. my 1 year old battery went poof when the BMW tech didn't plug mine in and i didn't realize it until i got 1/2 way to laguna with a leaking, bubbled battery in my trunk at the gas station.. lol

[TheStevo1000]

Thanks everyone for info. I removed all the airbags so I won't worry about that plug. It's easy enough to run a power wire to the IBS so I guess I'll do that.

Originally Posted by turbo_joe

I remove this entire unit to install my kill switch. Ditched the extra wiring and its never been an issue. I rain my main power from the battery to my kill switch. Kill switch feeds a fused distribution block. The block feeds the DME, Alt, fan, and an aux switch system I have for a handful of things (helmet fan, rear view cam, diff cooler pump/fan, etc.)

Side note: I run a small lithium battery, not the oem battery

turbo_joe, what fused distribution block do you use? Do you have a part # or link?
Thanks

[turbo_joe]

Originally Posted by TheStevo1000

Thanks everyone for info. I removed all the airbags so I won't worry about that plug. It's easy enough to run a power wire to the IBS so I guess I'll do that.




turbo_joe, what fused distribution block do you use? Do you have a part # or link?
Thanks

Using something similar to this, been on the race car for over a year with no issues

https://www.amazon.com/Recoil-Mini-A...1zcF9hdGY&th=1

[mikerunt]

Originally Posted by turbo_joe

Using something similar to this, been on the race car for over a year with no issues

https://www.amazon.com/Recoil-Mini-A...1zcF9hdGY&th=1

Do you have a photo of how it’s wired up? Or a diagram.

[turbo_joe]

Originally Posted by mikerunt

Do you have a photo of how it’s wired up? Or a diagram.

I can try to grab a photo at some point but my car is in my trailer right now.

But basically power in from the battery (going through my kill switch) and then power out is the same as the oem config. Only difference is moving the alternator feed after the kill switch instead of direct to the battery how it is from the factory.

[amg6975]

Originally Posted by turbo_joe

I can try to grab a photo at some point but my car is in my trailer right now.

But basically power in from the battery (going through my kill switch) and then power out is the same as the oem config. Only difference is moving the alternator feed after the kill switch instead of direct to the battery how it is from the factory.

I think this is reasonable. If it were my car I would add a big boi fuse right at the battery before going through the kill switch. Any sort of impact or something that would cause that unfused wire to contact ground would be pretty spectacular.

Did your car definitely have the IBS? Running find without it?

[turbo_joe]

Originally Posted by amg6975

I think this is reasonable. If it were my car I would add a big boi fuse right at the battery before going through the kill switch. Any sort of impact or something that would cause that unfused wire to contact ground would be pretty spectacular.

Did your car definitely have the IBS? Running find without it?

my car is a 2012, it had the same looking wiring as posted above. It is all gone now with the extra wire into the ground terminal as well. Runs fine. I have removed the entire airbag system and had it coded out as well.

[amg6975]

Originally Posted by turbo_joe

my car is a 2012, it had the same looking wiring as posted above. It is all gone now with the extra wire into the ground terminal as well. Runs fine. I have removed the entire airbag system and had it coded out as well.

Good to know the DME doesn't lose it's mind if the IBS isn't there.

I have no idea the rhyme or reason to what has the explosive disconnect either. My 1 series is a 2012 and had it, the 2013 M3 I bought to do the swap didn't. OP above and you don't.

[Project_Rogue_Motorsport]

What an interesting post 🤓

@DRLane thanks for the shout out 👍🏼

The removal of wiring in the E9X generation is really only limited to how far you are willing to live outside of comfort.

I prepare the stock harness completely out of the car and you can remove all the essentials down to just keeping the car running and driving without any issues.

I also build from scratch, GT4 base harnesses for the E92 M3 which utilises stock modules. For instance, the JBE, FRM, ABS, EKP, CAS, KOMBI and DME. These are very minimalistic compared to a stock harness, along with fitment being even easier over stock.

Then there is the FIA DTM spec harness that all runs from a PDM, Digital display, CANpad, standalone engine control and standalone ABS.

I am happy to point people in the right direction, but I hope you can all appreciate that I won’t be sharing all my secrets…

[Project_Rogue_Motorsport]

Originally Posted by TheStevo1000

Another question:

I'd like to get rid of this thing on the battery. I have a remote battery shutoff I will install. The battery power cables are obvious, but what about the 2 small connectors that are plugged into it? There's a single wire plug that goes to the negative terminal...Then a 2-wire plug that goes all the way to front into dash harness. Does anyone know what to do with those?

This can all be removed.

You would need to create a breaker box to supply the JBE, ALT, starter and electric fan. I personally create a whole new battery terminal into a maxi fuse panel and then it splits off in the relevant directions.

IBS sensor wiring is not crucial and can be removed if you know how to program it off in the DME.

Check the link below, around 30 seconds in you will see the battery relocation in this F-model. While not the same vehicle, the line of enquiry is similar. You can see the Liteblox mounted on the chassis and a circuit breaker below it.

https://www.instagram.com/reel/CyqQICxC30a/?igsh=MXNkeXQyeTJ5OWZ6bw==

[turbo_joe]

Originally Posted by Project_Rogue

This can all be removed.

You would need to create a breaker box to supply the JBE, ALT, starter and electric fan. I personally create a whole new battery terminal into a maxi fuse panel and then it splits off in the relevant directions.

This is exactly how I did mine

[amg6975]

Originally Posted by Project_Rogue

Then there is the FIA DTM spec harness that all runs from a PDM, Digital display, CANpad, standalone engine control and standalone ABS.

What ABS do you integrate? I've often wondered how far into racecar world we could go with the DME, DKG, and DSC modules. DSC always struck me as the biggest obstacle to true race car type systems with adjustable traction control and ABS.

I was just thinking the other day about how we could get a real braking system like the F82 GT4 integrated.