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The SLG BMW DCT Wiring Service

Th easiest way to get your BMW 7 Speed DCT swap out and driving!

We hope to make DCT swapping your project a much less daunting task. By following these instructions you will be able to remove the “mechatronics” sensor panel from the transmission. From there you can send it to us for all the wiring and soldering required. We will then send it back ready to go with easy-to-follow wiring documentation and a professionally made external wiring harness.

Once you receive the wiring kit back you will just need to plug the pins coming from the mechatronics board into the provided autosport connector at the transmission, attach power and ground leads, and connect to your vehicle's engine management. Once that is done your installation is complete and you will just need to start configuring the setup on your laptop.

If you would like a completely retrofitted transmission delivered to your door, we can arrange this as well. This popular option takes all the variables out of the equation and makes this a true “Crate Transmission”, or as we like to call it, “Transmission on a Pallet”.

Removal Process

Required Tools

1) Remove the side cover from the transmission. It is best to drain the oil from the pan first, be prepared for some to come out from under the cover when it's removed as well.

2) Gently pry up the white clip marked in green below. This is the mechatronic’s “Main Connector” lock.

3) Depress the tab marked in light blue. Once this is done you can pull out the Main Connector Plug. This will eventually be cut off and turned into a pigtail you use in the future.

4) Unscrew the fasteners marked in pink. Some will be retained by their plastic brackets. The black screws will come out and are different lengths. Either note their location or when installing just make sure they have about 10mm of thread depth before screwing them in. Watch to make sure O-rings on the bronze sensors under the mechatronics stay in place.

5) Remove the mechatronics panel from the transmission. The unit is located on two pins, so you may need to rock it back and forth a small amount before they slip off and the panel can pull free. Be firm but gentle.

The next step is crucial so you do not need to remove the clutch cover and clutch later down the road to complete the wiring. What you are going to do is mark 4 wires in the mechatronics main connector harness so that three wires are retained and are marked for future use. These wires go into a sensor that sits right behind the clutch.

First, we must understand the connector pinout. Pin locations are marked on the sides of the connector, and also on the diagram below. For reference, the diagram shows the pinout from the side the wires come out of.

6) Carefully remove the clear plastic cover around the wires.

7) Remove oil from the wires with brake clean and a microfiber cloth so they can be marked with a sharpie.

8) Find wires from pins 4, 5 and 6. Pin 5 will have two wires. Mark wires 1, 2 (both wires) and 3 respectively. Mark them about 4 inches from where they disappear into the transmission. You want to leave yourself room to solder to these wires later on. Pin 4 should be marked 1, the two Pin 5 wires should be marked 2, and Pin 6 should be marked 3.

9) Cut the wires you marked below their markings, and all the rest as close to the transmission as possible.

10) Unscrew the OEM wiring plug and remove it with all the wires you just cut. If it is retained by a couple of large wires, cut these as short as you can. They will not be used.

You will be left with three wires coming out in the mechatronics panel area. One of the wires marked “2” was removed with the OEM plug. You can throw out the OEM plug. You will connect to the three wires later on during the installation process. These wires measure the temperature of oil coming off the clutch and basket speed.

Now, the mechatronics sensor panel removal process is complete. You are now ready to pack the board and main connector harness together to send it to us for soldering and wiring. Pack carefully, these parts are fragile.


Unpack everything we sent back and get ready to start driving! But first, focus and make sure all processes are followed carefully as it is easy to make mistakes with so many wires.

1) Wipe down the transmission and mechatronics to remove any contamination.

2) Get plug ready and wire up to pins n, d, and c. Solder these to corresponding wires you marked while removing mechatronics. Solder c to marked wire 2, d to marked wire 1, n to marked wire 3. This covers the wiring needed for the sensor that is in the front of the transmission. No clutch removal necessary.

3) Retrieve the Main Connector pigtail. feed the wires through the transmission out the plug hole, one at a time. Follow the chart to place the right wires in the right positions.

4) Reinstall the mechatronics onto the transmission using the fasteners circled in pink below. Make sure the original o-rings that stayed on the transmission remain as you put it on.

5) Feed the large yellow power wires through the transmission to the center pins on the plug (m&r)

6) Using the chart below, feed the solenoid wires to their proper position in the plug (referenced in the excel workbook linked below). Solenoid positions marked below, S1, S2, etc. The first 4 are on the left, and the other 6 on the right.

7) Now make sure all the wires are fully seated into the plug. Once confirmed, take both hands and press the billet plug into the transmission. Some lube doesn't hurt. Place the locking ring on the plug and tighten down until there is good tension so the plug cannot spin.

8) Be careful to pull all wire slack into the mechatronics areas and zip tie them down. Loose wires risk being pushed forward into the clutch packs.

9) Clean the mechatronics cover seal and all mating surfaces. Reinstall cover, making sure to not pinch any wires.

10) Attach power and ground wires

11) Integrate your engine management and chassis electronics using Inputs/Outputs shown below.

You are complete! Your transmission is now wired and your ready to configure the GCU

Fill wiring documentation:

Wiring Service:

GCU and Wiring Service Kit:

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