This is a DIY guide to show you how to install a paddle shift steering wheel into a steptronic E46. My car is a 2003 330ci M-Sport, so I can't guarantee that yours will be the same. I take no responsibility for any damage caused to you or or car as a result of this guide
First, the theory. In a steptronic car, moving the stick to the left and knocking it up and down changes gear. This is done by a microswitch on each end of the switch. When the switch is pressed, a live signal is connected to earth and the car's gearbox ECU knows to change gear. This modification taps into this circuit. When the paddle is pressed, the very same signal is grounded via the steering wheel, giving the same effect.
First, you'll need to go shopping. You'll obviously need a steering wheel. I got mine from an E46 M3 SMG. A CSL wheel will do just as well, but you won't have the multifunction buttons, though you should be able to transfer yours over if necessary.
You'll also need to go shopping at your local dealer. Here's the list of part numbers and prices:
6x B61.13.0.006.663 - Bushing Contact - £1.10 each (I recommend getting 10 so you've got spares)
4x B61.13.0.006.664 - Pin Contact - £1.14 each (Get 10 again, just in case)
1x B188.8.131.529.091 - Steering Wheel Slip Ring - £76.91
1x B184.108.40.2060.696 - 2 Pin plug- £0.57
1x B220.127.116.115.611 - 4 Pin plug - £0.74
1x B18.104.22.1685.634 - 4 Pin Socket - £1.02
I got the 4 pin plugs above simply because I didn't feel happy about cutting/soldering the car's original wiring. This way the loom is revoveable should I ever need to take it out.
Finally you'll need 2 metres of 2 core cable. I got some from Maplins for about 80p per metre.
The first step in the conversion is to fabricate the new wiring loom. I started by putting the pins/bushings into the plug/socket housings. The shorter connections (the bushings) go into the plugs. The longer ones (pins) go into the socket. The pics below show the plugs and sockets in various states of construction.
You'll need to cut the cables to about 6 cm on each. Shorter is better, but I needed something to work with because I don't trust my soldering! I needed to make sure that I got the wiring joined correctly, so I connected the 4 pin plug and 4 pin socket together, then connected the top wire from each together with solder & heatshrink. I then did the bottom wires in the same way. The middle two need to be joined in a similar way, but the new 2 core wire needs to be connected as well. I heatshrunk the whole lot together and wrapped the lot in insulation tape. Before you wrap it up, mark the other end of the long cable (I used masking tape) so you know which core connects to which pin on the plug.
Now is the time to start taking the car apart. Start by disconnecting the battery negative lead. Tuck it out the way so it doesn't flick back and accidentally touch back to the terminal. If you don't do this, the airbag light will be triggered and you'll need it reset by a dealer/specialist.
Grab the back of the gearstick gaiter and pull up. This will release the clips and it'll lift up. Disconnect the wiring plugs and remember where they went. Next, remove the two screws you've just exposed, and lift up the window switch surround. Disconnect the plugs for the switches and move the trim section out of the way. You should now see the purple plugs for the shifter.
Next, remove the sunglasses holder under the aircon controls, by lifting the lid and pulling hard. You have to pull it harder than you think! You should now see two screws that were behind the sunglass holder, and two that were under the switch surround. Remove these and the whole plastic centre section comes out. Be careful here - the cigarette lighter cables will still be connected.
Next, remove the steering wheel. The airbag is the tricky bit. Behind the wheel are two small holes. Poke a flat blade screwdriver from the side and push the spring on each side to release the airbag. Have a look at the new wheel and you'll see the spring retainers. It's fiddly but can be done with a little patience. Once the airbag is out, prise up the back of each plug to release the clips and remove the plugs from the airbag unit. Put the airbag to one side.
Now, inside the wheel, remove the two plugs at the top. One is for the airbag, one for the multifunction computer. Next, get a 16mm socket and undo the bolt in the middle of the wheel. Remember the angle of the wheel to make sure the new one goes back the same way! Pull the wheel off and put to one side.
On top the steering column undo the screw, and underneath, push in the pins on the two trim fasteners. THe lower half of the steering column will now come away. I removed the lower dash trim above the pedals at this point but I'm not sure you need to.
Now is the best time to test fit the new wiring loom and cut it to length. You can then solder the remaining two bushing contacts to the loose end of the cable. Don't push them into the 2 pin plug housing yet.
With the new steering wheel in your hand, place it on the new slip ring (not attached to the car yet) and plug the paddle plug into the slip ring socket. Get a multimeter and set it on continuity (or resistance if you don't have it). Put one probe on the metal backing of the steering wheel, and the other on one of the pins on the back of the slip ring (on the 2 pin socket). Hit the paddles and work out which paddle is connected to which pin by looking for a change in the mulitmeter readings.
The back of the new slip ring is picture below.
So, we now know which pin on the slip ring corresponds to which paddle. On the wiring plug by the gear stick, the blue wire is up (+) - trace this up the new loom and fit the 2 pin plug the correct way round so that the blue wire is connected to the (+) paddle. If you get this wrong, you can always switch the pins in the plug by lightly pressing on the clips that hold them in.
Route the new loom through the centre console (this is why you removed the lighter socket and it's panel). Poke it up through the back of the steering column and zip tie it along the way to keep things neat.
By the gear stick, disconnect the purple plugs, and insert the new loom in between, like the pic below, and tuck it down out the way.
Time to replace the slip ring. Undo the 4 screws that secure the slip ring housing to the steering column and carefully remove the indicator stalks. Unplug the wiring for the slip ring, then replace with the new one, ensuring all plugs are back in, including the new one. Insert the indicators and screw the slip ring back in place.
Time to fit the new wheel. There are three plugs now:
Plug these into the slip ring, and do up the centre bolt - tightly! Make sure the wheel is in the same alignment as the old one now. I didn't, and had to straighten it later. Plug the airbag back in, push the clips ont he plugs down, and push the airbag unit back into place.
Now you can reconnect the battery.
At this point you should be able to start the car and test it out. Put it in drive, go left into sport mode and try the paddles. The stick should also still work. If this doesn't work, re-check the wiring plugs-you may have missed one.
Once you're happy, start re-assembling all the interior trim (the same way you took it off), then go for a drive. I challenge you to not smile at your now arcade-machine style gearchange
Sorry I didn't get more pics. I was too busy trying to get it done.
If you've got any specific questions, reply or PM me. I'll be happy to talk you through it.