[SSW]

Just received and installed the OEM alarm system in my pre-wired 2008 335i E90.

No instructions came w/the system, so this thread was very useful in getting me pointed in the right direction. Here are comments about my install which vary or add upon those provided by the OP.

1) The hood switch. All I needed to do was screw in the metal bracket holding the switch in place and take the tape off of the connector already wired into position, remove the plastic protective plug covering the connection and plug it into the switch. Easy, peasy!

2) The ultrasonic monitor. No tools are needed. In my E90, it's easy to just grab the light fixture from the front (towards the hood) and pull it down towards the rear. Out it came. The hardest thing to do was to get the plug for the module out of the holder in the light fixture. The fitting was really tight and I had to play with it quite awhile to get the plug out w/o breaking anything. The light fixture needs to be unplugged and removed from the car to facilitate the mounting of the module in it because the plug interferes with the positioning of the module which needs to be placed under the plug. Once the module is snapped in place, the module and fixture plugs are easily attached and the fixture is simply remounted by inserting the front of the fixture in the ceiling opening and just pushing it up to attach.

3) The siren mounting. This is the hardest part of the job. Make sure jack up the car properly and to wear disposable gloves for this because the well wheel is really dirty. I used a floor jack w/a jack pad adapter to lift the car from the side and put a jack stand under the differential housing (without putting any weight on it) as an safeguard.

You'll need some 8 & 10 mm sockets/wrenches for this part of the installation. You don't need a ratchet to remove the wheel well covering. You can loosen and reattach all of the nuts with just a socket handle (the screwdriver type). There are 5 10mm plastic nuts attached to studs protruding through various parts of the covering and 3 8mm machine screws along the lower rear edge of the wheel well. There are also 2 small (they look likes) torx screws holding the covering to forward edge of the wheel well, but it is unnecessary to remove them; you can just gently fold the bulk of the covering forward of the axle to get it out of the way with those 2 torx screws still attached.

After you have done that, you'll see a little pocket (looks different than what's in the OP's pics) at the top of the wheel well in which there's a wrapped connector and 3 studs where the mounting bracket is attached. You simply bolt the metal mounting bracket to the studs w/the supplied nuts; a ratchet is good for this. Then you attach the siren to the plastic mounting plate with a single nut. There are 2 ways to do this; with the connector location to the left or the right. The connector wired in my car ended on the left, so I mounted the siren w/the connector location on the left which followed the flow of the wiring and allowed more slack. The OP mentioned a "grommet" that was supposedly placed into the bracket for support but my set up did not have one.

Then came the most difficult task for me. The plastic mounting plate did not properly line up with the metal mounting bracket and I could only get one of the 2 10mm machine screws to seat in the treads on one side of the metal mounting bracket. A lot of fumbling resulted in one of the metal screws w/washer getting dropped repeatedly and "lost" occasionally in the nooks and crannies of the suspension, which required me to spend an inordinate amount of time looking for it and. After I located it, I would have never recovered it without the use of a telescoping magnet probe. Keep that in mind if you are having trouble getting your siren mounted.

In any event, I finally realized that I could bend the metal mounting bracket so that it would line up better with the plastic mounting plate and, after "eye balling" the position of the mounting holes by adjusting the ends of the bracket, I was able to get the 2nd machine screw into position and finally firmly attach the plastic mounting plate to the metal mounting bracket.

All that remained to be done was to reattach the wheel well covering, which required patience but was easily done by lining up the 5 holes in the covering which matched the 5 small studs in the wheel wheel and then reattaching the plastic 10mm nuts to the studs; just don't forget the 3 8mm machine screws that need to be reattached to the lower rear edge of the wheel well too. Rebolt the wheel to the axle (88 ft lbs torque) and all done!

When I locked the car w/the key fob, the red "clown nose" at the bottom of the mirror flashed rapidly for awhile and then slowed down to a slow continual blink which I assume is what it is supposed to do when the system is "armed." However, I did not get any beeps when I locked/unlocked the car and the siren did not sound when I waved my hand in the car through an open window. So, the next thing I have to do i to take it to the dealer or a qualified indy shop to have the alarm programmed to work properly.

Will let you all know how that goes after it's done.