Adding A Door Lock Switch

One thing I hate is trying to reach around over my shoulder and hit the door
lock stick on the door. I have a 2 door E36 so my stick is farther back
than the 4 door models. Well, I decided to put a new switch in my car that
would do the simplest of things, lock the doors. There have been comments
on safety issues and double locking the car, etc. This does nothing but
lock the doors, to unlock, you must simply pull the door lever. Simplicity.
Several people have asked me how I did it and I never really got around to
telling them, so read slowly. My total expenditure was less than fifty

First of all, I did it using the factory alarm connector. It is a plug in
solution that you can remove to work on it at a table or anywhere you please
without crawling around inside you car. The other benefit, and the one that
is more important to me is that you don't have to disconnect your battery.
So here we go, you will need a few parts and pieces to pull it off.

BMW ASC/T Switch Part # 61 31 1 390 806 Cost is $51.75 - 25% = $42.56

Factory alarm harness. I am sure you can pick one up at the dealership, I
will look into it for part numbers, but if you have a factory alarm, you are

A plug module to attach the switch to. I bought mine at radio shack as part
of a sound module (cat# 276-1324), it also came with some pins that I could
use, worked out great. It costs two dollars or so.

You will also need a soldering iron, hot glue gun, and some wire, (I used
black and red 20 gauge braided wire) and some screwdrivers to pull out the
glove box. Overall it is pretty easy work if you have pulled your glove box
before. Otherwise, check out dale's site for info on
pulling out the glove box.

Once you get the glove box out, you can get to the alarm and the harness,
you don't need to pull the passenger side kick panel or anything out, just
reach in and unplug the alarm harness. If you don' t have a factory alarm,
you can get the harness. If you alarm is aftermarket, modify it accordingly
at your own risk.

First step is to cut away some of the electrical tape or heat shrink on the
harness. Once you have it pulled back a bit, cut it away or tape it out of
the way. Now there are a bundle of wires, you will see a +12v yellow
battery wire with a fuse attached to it, and a black/yellow wire. Now the
black and yellow wire goes to the ZKE door lock input. Now you want to
spice into both of these wires. I just removed a little of the insulation
and wrapped a 3 foot section of new wire to the exposed wire. I then
soldered it, and shrink-wrapped it. Repeat this with the door lock wire, I
would recommend using a different color. Now that that's done, wrap the
harness with electrical tape (I would say heat shrink, but the factory used
electrical tape so I figured I could too.) You may wish to install blinking
hazard lights when alarm is armed/disarmed, you can see how to do that from
Dale's page as well. It is pretty simple and should take you 20 minutes if
you are extremely careful.

Next up is installing the pins on the ends of the wires. You need to make
a simple harness. Cut up the socket connector from the radio shack kit and
cut it down so it only has 6 holes in it. You are only going to use 4. Now
solder pins on to the wires you attached to the harness. Pretty simple.
Now, mark the switch with a felt pen or scratch a groove in it so you know
which way to insert the plug. Now if you look at the ASC switch, then you
will see the pins are numbered. You must run the two wires from the alarm
harness to pins 5 and 6. House work is now done, go back into the garage.

Go out to you car and reinstall the alarm harness. Run the wires along to
the center of the opening and then tuck them under the center console and
let them hang out a little next to the shifter. If you have a 5 speed, this
it will be pretty easy from here. Pull off the shifter knob, it will come
eventually, pull straight up. Now push in on the sides of the boot to
remove it. Now pull out the foam insulation piece. If you have an
automatic, then you will need to remove the OBC, reach into the sunglass
holder and there is a hold in the top. Put your finger in the hole and push
the OBC out, once it's out a little, you can grab the edges and pull it out.
Really not that hard to do, I wouldn't recommend using any tools as you
might scratch it and that will haunt you later whenever you see it. Now
that the OBC is out, pull up on the sunglass holder and the whole thing will
come out. Now tuck the harness under the center console and grab it with
your hand. You will need to tap into a dimmer switch, I just daisy chained
off of the cigarette lighter's light. Before you do this, make sure you
either disconnect the battery, or do what I did, and pull the fuses to the
cigarette lighter and the dimmer fuses. (Only about 3) Now you will need to
solder pins on to the light's wires. I just cut away some insulation and
went to it like before. I covered the interior with towels and then a piece
of cardboard so I would have something solid to work on. Now I placed an
inline fuse in each wire coming from the cigarette lighter light so I could
remove it and modify it in the future if needed. Now run the two wires from
the dimmer to pins 2 and 4 on the ASC Switch plug you created. Now, make
sure that all the wires are well insulated. Heat shrink tubing is cheap and
easy to use. Then you are pretty much done. Attach the plug that you made
to the switch, close the doors, and press the button. It should lock the
doors. Pretty neat huh? Now replace the fuses in the fuse box, and get
back into the car. Turn on the headlights. Does the switch light up?
Great. If not, you did something wrong back there. Check it. Now feed the
plug through the opening in the sunglass panel you wish to use, reinstall
the sunglass holder panel and the OBC, plug in the switch, and snap it into
the console. I personally put two gobs of hot glue on the harness to
prevent it from slipping out. It is not messy and easy to undo. Test it
again for good measure, and that's it.

A few words of caution. If you should ground the yellow wire, you are
screwed. It will take you hours to fix the problem. The doors lock when
you pulse the door lock pin in the ZKE with +12v. If you ground it, you
will blow a fuse in your auxiliary fuse box. Ask me how I know. If you do
by accident your OBC will not function nor will your alarm. If this
happens, email me and I will tell you how to get to the auxiliary fuse box.

So that's it. It shouldn't take that long. Be careful, and have fun. It
shouldn't be damaging to your car in any way. I am currently looking into
using a SMG switch from the EURO M3 Sequential setup for a door lock switch,
you can ask me about it later. It looks a little silly with two ASC
switches. If you don't have ASC, then it will look right at home, just don'
t tell anyone it locks the doors :)

If you have any questions, feel free to email me at I will be happy to help you with any
problems. Thanks go to John Firestone for his insights into the ZKE (BMW's
computer that controls the door locks, windows, etc.) And many thanks to
Stephen at South Motors BMW in Miami for the parts.

So, now you have a door lock switch, and it is 100% factory looking. You
can probably get by with a radio shack momentary contact switch and just
drill out one of the blanks, but I wanted my car to look factory. Use this
guide at your own risk, and good luck. I have also performed this operation
on a 97 M3 so I am pretty sure it will work on all E36s with an alarm port.
I plan on adding an HK on/off switch for my sub in the rear so I can turn it
off when someone occupies the rear of the car, a second sun roof switch,
using a visor switch (fits same holes as ASC switch) and a possibly a garage
door opener switch in the console using the SMG switch mentioned above. So
if you are interested let me know and I will post those procedures in the

I hope you enjoy your door lock switch, I tend to use mine more often at
night in the wrong part of town. Makes me feel better to know I can lock
the doors so fast, rather than have to fumble around if someone is harassing
me. I have had the modification done for 6 months on my 325is and 3 months
on my 97 M3 with no problems. Good luck.