DCT wiring harness thinning

[GeorgeH]

I was wondering if someone had a guide or information (in a thread?) about thinning the body wiring harness for a DCT equipped track car.

I see in build threads and various posts with people having ABS issues after thinning but nothing else really specific to the required components for a DCT car.

I was hoping to find some info to get me started and save some time otherwise I'll just start unplugging modules and seeing what happens.

So far I think I need the following modules at minimum:

• JBE
• DSC Sensor
• DSC
• DME
• DKG
• GWS
• KOMBI
• SZL/LWS

These I am not sure about:

• CAS - IIRC sends the Wake-up signal? Can this be coded out and a regular toggle switch be used?
• FRM - Any lights would be on a regular "toggle" switch
• LDM - Only needed for cruise?
• EKPS - Can I wire the fuel pump(s) to straight power or is the DME going to have an issue?

Any other input is appreciated, TIA

[e30gentry]

Originally Posted by GeorgeH

I was wondering if someone had a guide or information (in a thread?) about thinning the body wiring harness for a DCT equipped track car.

I see in build threads and various posts with people having ABS issues after thinning but nothing else really specific to the required components for a DCT car.

I was hoping to find some info to get me started and save some time otherwise I'll just start unplugging modules and seeing what happens.

So far I think I need the following modules at minimum:

JBE
DSC Sensor
DSC
DME
DKG
GWS
KOMBI
SZL/LWS


These I am not sure about:

CAS - IIRC sends the Wake-up signal? Can this be coded out and a regular toggle switch be used?
FRM - Any lights would be on a regular "toggle" switch
LDM - Only needed for cruise?
EKPS - Can I wire the fuel pump(s) to straight power or is the DME going to have an issue?


Any other input is appreciated, TIA

What I’ve been doing in a few hours of spare time here and there with my double hump, edc, DCT car is:
Leave double hump and edc alone for now(not sure what coilovers I want yet)
Remove every airbag, crash sensor, all rear audio/MOST system.
Then traced all wires and depinned from connectors.
Now for the EKPS, I believe unless you’re making your own fuel system you’ll need to keep this as it powers and regulates/ramps up/down signal as needed.
CAS/FRM and most others you’ve listed you’ll need to keep unless running different forms of standalone.
Alex and Roastbeef will probably have the most insight to all of this and I’d love to speak with both or either of them too

[GeorgeH]

Hey e30gentry thanks for the reply.

I was planning on doing what you noted above, but wanted to make sure I didn't miss something already listed on the forum.

Originally Posted by e30gentry

What I’ve been doing in a few hours of spare time here and there with my double hump, edc, DCT car is:
Leave double hump and edc alone for now(not sure what coilovers I want yet)

Sounds like our cars are similarly optioned, EDC, Doublehump, DCT, etc. What systems are you planning to retain aside the bare minimum to run the DCT?

Obviously if this was a 6MT car it would be much simpler but I just don't know how far the DCT system reaches to operate "properly." But maybe not, as I wrote that I realized aside from the DCT and GWS maybe everything else is still needed for a 6MT car?

Originally Posted by e30gentry

Remove every airbag, crash sensor, all rear audio/MOST system. Then traced all wires and depinned from connectors.

This is definitely the low hanging fruit and should be the easy part.

Originally Posted by e30gentry

Now for the EKPS, I believe unless you’re making your own fuel system you’ll need to keep this as it powers and regulates/ramps up/down signal as needed.

I put together an S85 swapped E46 and it was on a stock DME through an Awron gateway and then used a standard fuel pump relay. I wasn't sure if that Awron gateway was doing something in regards to the DME/Fuel pump or if the DME even cared the EKPS wasn't installed (faults suppressed).

Originally Posted by e30gentry

CAS/FRM and most others you’ve listed you’ll need to keep unless running different forms of standalone.

What do you mean by this? What is the FRM sending that the DCT needs?

I assume CAS is sending some kind of Wake-Up signal out to other modules. But aside from that I wasn't sure what else it did. We've got the ability to CAS delete the MSS60 DME as far as the key/anti theft system is concerned but again I wasn't sure how far it reached beyond the WUP.

Originally Posted by e30gentry

Alex and Roastbeef will probably have the most insight to all of this and I’d love to speak with both or either of them too

Maybe they will chime in. In the meantime can you be more specific on Alex's user name as there are bunch on the forum. I'll spend some time looking through their posts and see if anything was mentioned.

[e30gentry]

I am only temporarily keeping the double hump/Idrive as well as EDC.
I just do a test run after thining the majority of the harness with no issues so now it’s time clean everything up.

If you get definitive answers on the FRM and everything else I’m all in and want to go the same route, this box of harness is crazy heavy in my opinion and I’d love to add to it.

I’m happy to help how ever I can on what I’ve done so far on the car

[GeorgeH]

e30gentry I am going to lose my double hump/EDC too.

Full disclosure I have an E93 that I am using as a donor and am putting the drivetrain in an E46. My plan is to sort out the wiring in the E93 before swapping it into the E46.

Right now I am thinking I would keep the MRS, IHKA, GM, LCM and Kombi (it will be tucked away, purely as a diagnostic component) from the E46 and then everything else will be E9x.

[amg6975]

Originally Posted by GeorgeH

These I am not sure about:

• CAS - IIRC sends the Wake-up signal? Can this be coded out and a regular toggle switch be used?
• FRM - Any lights would be on a regular "toggle" switch
• LDM - Only needed for cruise?
• EKPS - Can I wire the fuel pump(s) to straight power or is the DME going to have an issue?

You absolutely need all those, although I don't think the M3 has an LDM? Or maybe only early cars.

Car won't start without CAS, Lots of things won't work without FRM, DME will likely freak out if it can't see EKPS.

Airbag, Roof Control, iDrive, and anything audio can go. Most everything else has to stay, but you can remove some individual wires here and there.

[GeorgeH]

Originally Posted by amg6975

You absolutely need all those, although I don't think the M3 has an LDM? Or maybe only early cars.

Car won't start without CAS, Lots of things won't work without FRM, DME will likely freak out if it can't see EKPS.

Airbag, Roof Control, iDrive, and anything audio can go. Most everything else has to stay, but you can remove some individual wires here and there.

Appreciate the reply, somehow just now seeing this.

I wasn't sure about the LDM, I was going off the technical documentation but haven't dug into the donor car yet.

CAS prevents starting on a "stock" car, but with CAS delete in the DME it would start, essentially making it a standalone. I wasn't sure if I needed the CAS for anything else besides the 15 WUP signal?

What won't work without the FRM? It looks like maybe the door latches are identified through the FRM which would prevent beinge able to select "Drive?" Anything else?

[amg6975]

Originally Posted by GeorgeH

Appreciate the reply, somehow just now seeing this.

I wasn't sure about the LDM, I was going off the technical documentation but haven't dug into the donor car yet.

CAS prevents starting on a "stock" car, but with CAS delete in the DME it would start, essentially making it a standalone. I wasn't sure if I needed the CAS for anything else besides the 15 WUP signal?

What won't work without the FRM? It looks like maybe the door latches are identified through the FRM which would prevent beinge able to select "Drive?" Anything else?

I think essentially not much will work without the CAS. There are several wakeuplines that are sequenced. Maybe you can get around it but I'm not sure. These modules weigh almost nothing and are by far the easiest, most reliable way to make the car work.

I have a feeling, again, the car will not be happy about the FRM being gone. It is responsible for all lighting functions, as well as general car operation. It's one of two places the VO and VIN gets stored (second is the CAS) so if you remove these I think you're going to have a problem.

Unless you're ripping everything out and running the DME completely alone the amount of work you're going to need to do to properly remove all this (if you can at all) is not worth the 4-5 lbs.

Removing the ABG module, airbags, and their associated wiring is literally half the weight of the whole car's electronics and can be done without any issues to the car other than turning off the check in the KOMBI. Second most beneficial is the audio harness, and then the whole roof harness. After that you have very little harness left and everything will still work as it should. After that your time and money can be much better spent elsewhere.

[GeorgeH]

Originally Posted by amg6975

I think essentially not much will work without the CAS. There are several wakeuplines that are sequenced. Maybe you can get around it but I'm not sure. These modules weigh almost nothing and are by far the easiest, most reliable way to make the car work.

That's what I am wondering, if there is a work around?

Originally Posted by amg6975

I have a feeling, again, the car will not be happy about the FRM being gone. It is responsible for all lighting functions, as well as general car operation. It's one of two places the VO and VIN gets stored (second is the CAS) so if you remove these I think you're going to have a problem.

Unless you're ripping everything out and running the DME completely alone the amount of work you're going to need to do to properly remove all this (if you can at all) is not worth the 4-5 lbs.

This is not staying in the E9x chassis so I don't care about lighting or general car functions. The weight is not as important as having to add the items into the E46 that modules need.

As an example if the FRM is only providing the door lock status to make the DCT work I would prefer NOT to have to retrofit it and spoof the lock status (I'm not putting E9x latches in the car). And really along those lines I guess this all applies to an E9x race car as well. My goal is to have only what is needed to make it work, nothing else. If I have to install the FRM and then jump the lock status to show closed I will, just prefer not to if I don't need to.

*Note, lighting, body components and airbag system are going to stay E46, everything else will likely be E9x.

[amg6975]

Originally Posted by GeorgeH

That's what I am wondering, if there is a work around?



This is not staying in the E9x chassis so I don't care about lighting or general car functions. The weight is not as important as having to add the items into the E46 that modules need.

As an example if the FRM is only providing the door lock status to make the DCT work I would prefer NOT to have to retrofit it and spoof the lock status (I'm not putting E9x latches in the car). And really along those lines I guess this all applies to an E9x race car as well. My goal is to have only what is needed to make it work, nothing else. If I have to install the FRM and then jump the lock status to show closed I will, just prefer not to if I don't need to.

*Note, lighting, body components and airbag system are going to stay E46, everything else will likely be E9x.

Oh. I think you're going to want to put in the CAS, DME, and DKG. You may need the KOMBI, I'm not sure exactly what (it's on my list) but the DKG uses something from the KOMBI and will be pissed without it. You're going to have a million errors but it may work? I think the DCT may also want to see the DSC wheel speeds.

People have done this before...

Might be easier to just go standalone for the engine and DCT.

[GeorgeH]

Originally Posted by amg6975

Oh. I think you're going to want to put in the CAS, DME, and DKG. You may need the KOMBI, I'm not sure exactly what (it's on my list) but the DKG uses something from the KOMBI and will be pissed without it. You're going to have a million errors but it may work? I think the DCT may also want to see the DSC wheel speeds.

People have done this before...

Oh ya, its gonna need a lot more than what you listed. If that was a 6MT car then I would just set the DME up with a CAS delete an call it a day.

But my plan is to swap everything I have to from the E9x. Technically there will be (2) Kombis in the car, E9x and E46 as they are both the gateway for diagnostic equipment to talk to modules.

Originally Posted by amg6975

Might be easier to just go standalone for the engine and DCT.

Definitely won't be easy, but I want OE drivability. No aftermarket setup is there yet. Maybe in a few years, but not quite now.

[amg6975]

Originally Posted by GeorgeH

Technically there will be (2) Kombis in the car, E9x and E46 as they are both the gateway for diagnostic equipment to talk to modules.

Not in the E9x. The Radio and JBBF do the diagnostic distribution. I think you can delete the KOMBI in a manual car but the DCT throws a fit without it.

A KOMBI delete module is on my long list of crap to get to.

[GeorgeH]

Originally Posted by amg6975

Not in the E9x. The Radio and JBBF do the diagnostic distribution. I think you can delete the KOMBI in a manual car but the DCT throws a fit without it.

A KOMBI delete module is on my long list of crap to get to.

Oh yes, you are correct.

Either way I assumed the Kombi was sending some kind of pertinent info to the DCT.