1. One Momentary Start Button - ( I used a Z8 Start Button from Pacific BMW p/n 61 31 8 377 343 Z8 )
2. Two Contact Pins/Wires - ( Again I purchased from Pacific BMW p/n 61 13 0 006 665 )
3. One 30A/12 Volt Relay - ( Can be purchased at any local car parts store such as Autozone or Advance Auto Parts)
4. One Roll of Electrical Tape
5. Spool of 14-16 gauge wire
1. Wire Stripper/Crimper
2. Wire Taps - (Optional, can use electrical tape also)
3. Wire Cutters
4. Wire Ties
5. Soldering Iron
6. Dremel w/ Grinding Stone
First thing you’re going to need to do is remove your OBC and Console to remove the cigarette lighter so you can modify the hole to fit your new start button. To do this use your finger and pull the OBC out through the hole in sunglass holder. You may disconnect it if you would like, it will not retain its memory though.
Next you want to pull out your console, be careful when pulling this out, it should just pop out but there will be some wires you'll need to disconnect: cigarette power, heated seats, and a light bulb. Once this is out pop the cigarette lighter out from the console. Push up on it from the bottom, will take a little bit of force but it will pop right out.
Now to the dremel. Use the dremel with some type of grinding stone to make the hole a good size for your start button. I made the mistake of using a carbide cutter, just go with a good grinding stone, it will be much easier and look much better, notice how mine isn't a perfect circle. Not to worry though if you make a little bit of a mistake, the start button will cover it up and you won't be able to tell at all. Once you think you have the correct size put the start button in to test for a good fit.
Now to the fun stuff. You’re going to be spending a lot of time under your steering column so what I recommend to do is remove your driver seat. Much easier for me since I have racing seats and past experience with it but it really made it so much easier to do to be able to lay down in the car and have plenty of work space. Now is time to remove the driver side lower dash panel. There are three screws, one to the left and right of the steering wheel, and one closer to the gas pedal.
Next step is to remove the the metal panel that is protecting all the wiring. There are 3 bolts you'll need to remove.
Now its time to break out the nifty relay you bought. Below is a wiring diagram for the relay. I soldered a few of the connections to ensure good quality, others had to be done with electrical tape just because I wasn't about to try doing some soldering with my face under the relay and in the midst of about 1000 wires.
Here goes nothing, time to make the first cut. Find the green wire and give it a cut, in the middle so you have some slack on both sides. With a piece of wire about 4" long tap it into the green wire and tape all ends together. With your piece of wire you tapped into the green wire connect it to the relay as shown on the wiring diagram (see above). Below is a picture of the ignition harness, this is where the wires you are tapping terminate. Your going to want to cut them down towards the harness that goes towards the starter as shown in the second picture.
Next is to cut the Yellow/Black wire. If you want your car to start with only the button ( which is what I did ) tape off the end of the wire that goes towards the ignition. If you want your car to start with either the key or the button use the same tap as you did in the previous step. Tap another 4" wire to the side of the Yellow/Black wire that goes towards the starter. Connect it to the relay as shown in the wiring diagram (see above).
Now run the contact pin from the relay to up to where the start button will be located. ( If you’re using the Z8 Start Button connect the contact pin to pin number 1. Your other contact pin just needs to be ground. So find a good place to ground it and connect this pin to pin number 4 on the start button
Step 10:Now go ahead and put your key in and turn it to the on position and press your start button. If it doesn't work right away ( which mine didn't ) check your ground to make sure it has a good ground and from there check your wire taps.