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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > DIY Guides > DIY: E93 Alarm Motion sensor

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      02-22-2008, 01:27 PM   #1

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DIY: E93 Alarm Motion sensor

FINALLY,..It took me some time but I figured out how to wire a motion sensor into the OEM Alarm on the Convertible. Works well but I do need some tweaking,..so any input is appreciated. As you may know the US dealer installed alarm does NOT come with motion sensor despite what the owners manual says. I wanted to be able to leave my car window or top down and still have alarm set (although I rarely do leave car with top down). Its a bit long but I will post pictures soon. For now here is the DIY

Plan: place DEI 508D sensor near center of car and wire the BLUE trigger wire to the hood sensor. Use the BLACK ground wire to appropriate ground on the car (I used engine bay screw). Terminate the early warning (1st stage) GREEN trigger wire. Run the RED power wire to always on source fuse tap at fuse box.

Disclaimer: I am NO electrician or mechanic. I assume NO liability from you trying to do this and messing up your car in any way! Use this information at your own risk.

Here's How I did it:

Car: 2007 335 E93 Convertible with Step tranny NO I-drive.
Difficulty (0-10) = 3
Time ~2 hrs.

1. You will need a motion sensor with a trigger. I bought the DEI 508D RF field Motion Sensor (Amazon.com~$35).
2. Wire 18g Black (~20ft) = $5 (Optional Blue wire as well)
3. 3M Butt/Splice connectors (~$3), Quick Connects ($3), Spade connector (~$2)
4. Add-a-Circuit from Autozone (~$4)
5. Wire stripper/cutter, Crimping tool, Flathead Screwdriver, Ratchet set, Hex key

1. Unlock all doors, Glove compartment, Hood, roll down windows and leave trunk open for ease. Disconnect Negative terminal of battery (Need 10mm socket) in Right side of trunk under 2 panels (1 gray and 1 black).

2. Use fishing line or extra wire, tie a handle to the ends of the DEI 508D so you can retrieve it later if you need to service the sensor. Open the boot over the emergency brake using a flathead screwdriver and pulling,... it will pop off easily.

3. Pull straight up on shift knob (HARD) and pull up on back right corner of shift boot cover to pop them off as well. Open center console armrest top door and pull hard on rear part of center console trim to pop out. Make sure to keep the foam pads that go with the clips underneath.

4. There are 4 clips/plugs you need to unhook. Starting from rear going forward they are (in order) a black one that disconnects by pulling to driver side, blue one on the driver side that disconnects by pulling straight down, white one on the passenger side that disconnects to the front of the car, and 3 prong white plug under ashtray that disconnects by squeezing sides together and pulling backward. Now center console trim is free to set aside. Notice a hole in the rear of where the center console trim was (under the convertible top switch). This looks into the emergency brake area.

5. Place the sensor in the hole between the E-brake and center console and fish wire through the hole to center console area underneath where trim will go back. (see pics when I post them soon). Cut the terminal plug on the end of the wire furthest from the sensor. Run wires toward the front and along path of other wires in the center console area. Make sure the wires do not get caught on shifter mechanism. Run wires under horizontal plastic piece at the very front of the center console area. Pull ONLY the red wire away from the green, blue, and black wires.

6. Unscrew the 2 Hex screws holding underside of glovebox in place and the 3 hex screws on the underside of the driver side dash panel. You will need a 7/64 Hex Screw Key.

7. The green wire is an early Warning sensor trigger that goes off if you have the ability to give a warning chirp or voice command like "stay away" on your alarm. We don't have this feature on our BMW OEM car alarm and it was too much of a pain in the ass to wire for that so I didn't use the green wire. At this point I terminated the Green wire from the sensor and wrapped with Electrical tape. You can either run the ground (black) wire to the engine bay and ground there or run it to the fusebox and use a screw there. I chose to run the ground to the engine bay.

8. The blue wire and black wire are now running together and will go to the engine bay. The Blue wire is a second stage trigger if an object moves within the cabin of the vehicle. (Green was first stage for outside the car). We will eventually hook up the Blue wire to the hood sensor switch.

9. Tuck the Black/Blue wires in the side of center dash trim and run toward driver side under dash. Now use the 18guage wire (any gauge wire between 18-22 is fine) and cut 2 strips about 10 feet long each. Since at this point I decided to use both black wires I needed a way to discern ground from trigger as I fished the wire through the firewall. I chose to strip both ends of one wire and leave the other wire unstripped. (It would be easier to use 2 different color wires but I didn't feel like buying more wire.) My Stripped wire was to become my Trigger and the unstripped one was to be the Ground wire.

10. After removing the under dash cover in the top left corner (over the left foot rest) you will see a circle about 3 inches wide with 3 bundles of wires going through the firewall and into the engine bay. The top right portion of the circle (about 1 o'clock position) there is a hole that is plugged up but with no wires running through it. Go to the engine bay and remove the front and back clips on the black cover in front of the windshield (rearmost portion of engine bay). This covers the ABS system and has a rubber clasp you will need to move backwards to fully remove the cover. (this is same cover that you may remove with Procede install)

11. Using flash light you will see a small rubber finger like projection through the firewall at the same level as the hole I described in the above step. You can either cut this off (my scissors wouldn't reach) or do what I did. I braided the black wires together and taped the ends together for the end going through the firewall. Then I used a long flathead screwdriver to poke my way through the hole from the drivers side under the dash (pedal) area. Pass this repeatedly until the hole is big enough or push the 2 black wires through the hole with the tip of the screwdriver. Retrieve them on the other side - Pliers help do this.

12. Now you have your wires and you will run one to the ground. I chose a ground just above a common ground site on the left wheel well. You will see a screw sticking out of the wheel well toward the engine bay. There is nothing on this screw. Another ground site is just underneath this screw and that one has many ground wires going to it. I chose the top one and stripped the wire and crimped a spade connector to the ground (remember it was unstripped going through the firewall) Use a 7/16 nut and socket to connect the spade ground to the screw. I ran my ground under the trim along with the other wires in this area so it wouldn't get pinched with closing the hood.

13. Now snake the already stripped Trigger wire to the hood sensor located at the rear of the engine bay immediately in front of the black cover you took off. It has a black fingerlike pressure switch pointing straight up with 2 wires connected to it. Squeeze the top of the clip and disconnect it from the hood sensor. Now strip back some of the electrical tape to expose about 2 inches of the 2 wires. There is a PURPLE wire with a GREEN stripe. This is the trigger for the hood switch (I assume the brown is a ground for the hood switch). Now use the 3M quick Connects to connect the trigger wire from the firewall to tap into the purple/green wire on the hood switch. Read instructions on the package if you dont know how to do this.

14. Now use butt connectors and strip the blue sensor wire, black sensor wire, and black firewall ground wire. The butt connectors are doubly crimped and the blue goes to the trigger wire and the black goes to the ground. You may have a foot or so of extra sensor wires. I just cut the extra off.

15. Now run the red power wire from the sensor to the fuse box and strip the wire. Cut any excess wire.

16. Use the Add-a-Circuit to tap into the #19 fuse (7.5A fuse). The positive end of the fuse slot is the left side slot. So, make sure to place the Add-a-Circuit power on the left side of the fuse. Crimp the Red wire to the Add-a-Circuit.

17. Set the sensor to just under maximum sensitivity by adjusting both knobs on the sensor. I taped the retrieval wire from the sensor ends to the E-brake handle in case I need to adjust the position or sensitivity of the sensor.

18. Tidy up with electrical tape everywhere. Replace all covers and screws. Reconnect battery and you now have motion sensor on your convertible!

Last edited by 2007_E93; 02-23-2008 at 08:59 PM.
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