N55 - DCT Conversion?

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Beygan

New Member
Sep 26, 2019
3
Currently in the process of preparing for a conversion to DCT.

The current car in question is

not an N54
equipped with MEVD17 instead of MSD81.

Anybody been in this situation and completed the swap?

I’m trying to figure out, without the proper resources, the required wiring, as well as coding to make this work.

Currently the project includes the following acquired components, as well as known components worth acquiring, respectively:

-DCTransmission
-DM Flywheel
-2.56r Pumpkin/Diff
-DCT Shifter Assembly
-DCT Shift Knob
-DCT Shifter Wiring (to CAS and ECU)[from an N54 MSD81 335is] so NULL

-Transmission Wiring Harness
-DCT Shifter Wiring (from N55 DCT with MEVD17)
-Engine Wiring Harness (potentially)

I’d appreciate any useful input. This is definitely be something worth surfacing.

-Beygan
 
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doublespaces

Administrator
Oct 18, 2016
8,009
AZ
If you don't have a flywheel, I have an OEM DCT dual mass flywheel for sale out of a 2012 135i.

Get the transmission wiring harness from an N55 DCT. The trans harness on the N54 goes directly into the ECU box and mounts to a mini patch panel. Then those wires go off to their respective places such as the ECU/GWS etc.

If you get one from an N54, there are some wiring differences since the ECU/DME box is not the same place and physically looking at the harness I can tell they are not the same. I think the N55 puts the DME on the driver side on the intake manifold which may be part of the reason.

The 'dct shifter wiring' is kind of vague. I found that from the GWS(the shifter base) the wiring off that connector shoots out in a few different directions to the places you need so its not so much one harness. Instead of getting the wiring, which is probably just the last branches of a larger harness, you could just make your own using newtis.info

I am curious what that wiring looks like as I was assuming its intertwined with everything else.
 

AJL

Private
May 11, 2017
40
First, welcome to SpoolStreet :)

Here’s the link to the thread where I posted the shifter re-wiring plan that I ended up using.


Basically it just involved taking the existing auto shifter connections and remapping them to the 10-pin DCT plug to match the correct pins on the engine harness that you’d be replacing. I did have to run 3 new wires: a PT-CAN twisted pair, and awake up signal wire to under the passenger footwell.
As @doublespaces said, you can use newtis.info to verify everything for your specific application. But based on our conversation over on e90post, we have pretty much exactly the same car.
 
Last edited:
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Beygan

New Member
Sep 26, 2019
3
Thanks for the welcome AJL. I’m very excited to be on Spool Street and joining in on some fun too from my own car.

Thanks as well for such support, @AJL @doublespaces I’ve reviewed the diagrams and it doesn’t seem so difficult after you’ve mapped it all out.

From the three plugs from the car to the three plugs from the DCT components, it just takes a bit of patience to run the wires through to the right places.

I might need to find an electrician to help. I inspected the wiring from the shifter harness I bought from a wrecked 335is. The plugs are the same but the color-coding on the wires differ.

I’ll just have to make use of the connectors and as you’ve said make a new harness. I’ll look into this.


Additionally, it appears I’ve got a missing connector (DCT side). DCT Park Lock, X11150. This is gonna be fun.
 

Attachments

doublespaces

Administrator
Oct 18, 2016
8,009
AZ
It's worth noting the 335is shifter knob is not the same as the one for the 135i. The base plate is shaped differently so the shift boot will be wrong.
 

Beygan

New Member
Sep 26, 2019
3
It's worth noting the 335is shifter knob is not the same as the one for the 135i. The base plate is shaped differently so the shift boot will be wrong.
I see.

I locked down the depicted assembly, lockout, and knob all from the same source. This one’s from a 335is. I presume they will fit right in the E90. Hopefully this rules that out.

Main concern still it seems to me, is the wiring.
 

doublespaces

Administrator
Oct 18, 2016
8,009
AZ
I see.

I locked down the depicted assembly, lockout, and knob all from the same source. This one’s from a 335is. I presume they will fit right in the E90. Hopefully this rules that out.

Main concern still it seems to me, is the wiring.
If you have an e90 then it will be fine, that is what you want.
 

AJL

Private
May 11, 2017
40
I see.

I locked down the depicted assembly, lockout, and knob all from the same source. This one’s from a 335is. I presume they will fit right in the E90. Hopefully this rules that out.

Main concern still it seems to me, is the wiring.
Yes the 335is shifter will fit the e90, so you've got that part correct. The wiring was daunting to me as well, but it really ended up not being too bad once I got started on it - The only wires you'll need to mess with for the entire swap are for the shifter.
 

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