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Our future: swap SMG for 6-speed manual?

254K views 504 replies 103 participants last post by  jbash87 
#1 ·
So let's say you want to keep your amazing M5 for a long time ... like 10 or more years. At some time you will be long out of warranty and may face a SMG transmission failure. At that point do you think you might consider swapping out the SMG for a 6-speed manual? Considering that parts for the 6-speed cost something like $4,500 versus $8,900 for the SMG?

I enjoy reading about the classic BMWs from 20 to 25 years ago such as the E24 6 series and the E28 5 series ... and to keep those machines on the road they are always swapping out for parts from other BMWs, especially converting from automatic transmissions to manuals.

So I started to wonder ... what steps are we going to need to take to keep these beasts on the road long-term? Your thoughts?
 
#494 ·
Based on how newtis and ISTA lay things out there won't be a pinout for this connector, or any connector really. Also, the X6021 isn't the manual harness connector. The X60681 is.

The RPM sensor is not part of the X60681. It is it's own connector and goes to a few places.

What specifically are you looking for?
 
#495 · (Edited)
Sorry - I should have been clearer. By 'manual harness' I mean the harness that goes between the manual transmission harness (#23017840637) and the DME box in cars with a manual transmission.


Bicycle part Bicycle handlebar Electrical wiring Diagonal pliers Input device


So I am looking for the pin assignments for the bottom right 8-way connector at the DME box side of this harness - not the X60681 connector.

It appears from the above that the signals for all three connectors on the manual transmission harness (temperature, neutral, reverse) and the RPM connector on the DME-side harness end up in this 8-way connector.
 

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#496 ·
Where did you get that harness from? Did you pull that out of a manual car or did you make that?

Granted I built my own wiring diagram for my swap, so I'm not sure what method you're following. However, the wires ultimately have to end up in the same spot. The X6021 only gets 1 wire from the manual harness and that is RPM sensor 3. The rest of the wires go other places.
 
#499 ·
They do not all go to one connector as the photo would elude to. Maybe that is why I'm confused that you're asking for the pinouts for that connector?

E39Source's video traces the wires from where they are to where they go. He re-pinned the SMG (car side X11) harness rather than the manual harness (X60681) as I did. So I cannot answer your question directly.
Note the X60681 plugs into the X11 on a manual conversion.
 
#500 ·
They do not all go to one connector as the photo would elude to. Maybe that is why I'm confused that you're asking for the pinouts for that connector?
I am also confused! I think the source of my confusion is that the above picture suggests that there is a manual harness where all the transmission sensor wiries do terminate in one connector.

I also found these harness pictures from an ad for an M6 manual transmission (which I assume has the same harness as the M5 manual):

Motor vehicle Automotive tire Gas Automotive wheel system Machine



Wheel Tire Automotive tire Motor vehicle Vehicle


As you can see, the harness pictured here is identical to the one pictured earlier in the thread and has a single black DME-side connector that seems to contain all the manual sensor wiring.

If this is correct (and I am not 100% sure it is), it might imply the existence of an additional manual-only connector and harness that will plug into this black connector in the DME box.

My goal is to see if I can replicate the stock manual DME-side wiring and ideally come up with a solution that involves only wire repinning and rerouting with no splicing.

In any case, thanks for your help so far!
 
#502 ·
I did this a few months ago for my manual swapped 06. I hooked the manual harness to the old SMG harness. Required 1 re-pin on the SMG harness side, as one of the pins to hook to the manual was blank.

Then, I traced all the wires in the SMG harness I was using back to the DME box, using a continuity tester (negative clipped to SMG harness under the car via a jumper, positive in the DME box - where I found the wire in the old SMG harness.)

Once I had all the wires traced down to the DME box, I repinned / spliced into the DME harness (as described in e39source video). Then I spliced one wire (reverse sensor) into an abandoned SMG wire into the cabin (previously used for the DME shifter). That wire (now reverse sensor inside center console) was un-pinned from the SMG shifter harness and spliced under the dash to the LMA (lighting module). In the LMA, you pin the wire for reverse sensing via switch (as opposed to via CAN-BUS as it is for SMG). This is needed to get reverse lights working for the manual.

I also made my own wiring harness diagram based on my re-pinning and testing. If I had to do it all over again, I would note what wires are in the SMG harness and re-pin the manual harness to the easiest wires to deal with in the DME box. Someone could do a diagram and instructions for replicating this process, and the re-pinning. Would be nice to have on paper.

One last thing - you cannot easily buy the manual --> DME harness to simplify this process. It is part of the main engine harness. I think it is easier to just use the abandoned SMG plug and trace it down in the DME box under the hood.
e39source's video on this is the best resource - just go slow and verify everything he says. Especially the correct pin shape for the DME harness on the one new pin you have to insert!!

Happy to try and answer anywhere you get stuck or have questions!

@jbash87 here's another post I wrote (closer to the time when I did the wiring!!) https://www.m5board.com/threads/my-smg-→-6-speed-manual-conversion.614913/post-7704263

one other thought - there are several wires which trace back to the SMG harness in the DME box, but are bundled together (I think to ground). I separated those from other wires they were connected to, and spliced on jumpers to get them over to the DME harness..

That's the last of what I remember from the wiring!! 🤣
 
#503 · (Edited)
one other thought - there are several wires which trace back to the SMG harness in the DME box, but are bundled together (I think to ground). I separated those from other wires they were connected to, and spliced on jumpers to get them over to the DME harness..
Yup - while the E39Source videos are invaluable, they gloss over a lot of details.

I bought a used SMG harness to experiment with (they are cheap and readily available on eBay). It revealed a lot of those details.

There are two terminated wire bundles that need to be pulled apart on that harness.

As you mentioned, there is a terminated ground wire bundle on the DME side of the SMG harness with 5 yellow/brown wires. These need to be pulled apart because some of the wires will be carrying non-ground signals from the transmission harness in the manual rewiring. This bundle must be reassembled with the remaining ground wires afterwards.

There is also a similar terminated wire bundle on the SMG harness with 4 green/red wires that must pulled apart so that the individual wires can be used.

The real problem for someone attempting this conversion is that there is no distilled information (a single wiring schematic, for example) and the knowledge is spread out over hours of videos and many board postings. And, while nicely detailed, the way the wiring and connector information is spread over a multitude of diagrams in the ISTA software can also be infuriating.
 
#504 · (Edited)
To clarify: By terminated wire bundles, I mean the wires going into the yellow and green caps pictured below. The wires are crimped together inside these caps.

In SMG cars, three red/green wires enter the yellow cap from the SMG harness and one red/green wire exits to position #33 of SMG connector X70014.

Four yellow/brown wires enter the green cap from the SMG harness and one yellow/brown wire exits to position #4 of SMG connector X70014.

When a manual transmission harness is plugged into the SMG harness some of the wires in both of these bundles will carry signals from the transmission sensors.

So these bundles must be pulled apart and the wires repurposed when doing a manual rewiring.

Light Electrical wiring Electronic device Wire Auto part
 
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