proper installation of the DEI shock sensor revealed

Do you have any problems opening and closing the trunk alone w/o disabling the alarm? I have mine connected to the hood pin and when I close the trunk w/o disabling the alarm, the alarm go off. It looks ghetto

Originally posted by peterpan223
Do you have any problems opening and closing the trunk alone w/o disabling the alarm? I have mine connected to the hood pin and when I close the trunk w/o disabling the alarm, the alarm go off. It looks ghetto

never tried it, but, i would imagine the alarm will go off unless you hit the unlock button first to dis-arm the alarm before you "pop" the trunk. the shock sensor will for sure pick up the impact of the trunk closing. if you think it looks ghetto, then why do you open it before hitting the unlock button??? opening the trunk alone will not disable the hood pin, so the sensor will still be active...

The trunk button on the key is designed to pop the trunk in just a thouch of a button, not two. That's why I keep forgetting to press unlock and pop the trunk, especially when my hands are full of stuff like grocery bags.

Anyways, someone told me that if I mount the sensor to the tilt sensor, I will be able to disable the sensor everytime I pop the trunk since the tilt sensor is designed to do that.

but thanks anyways

I used the RadioShack taps, yours look much better.

Originally posted by cls1000
I always use 3M wire taps. I'm not a fan of cutting wires, especially facotry ones, and the t-taps are your best alternative. No, I didn't think about putting it in the trunk because that defeats the whole purpose, you might as well leave it under the hood. the idea is having it mounted in the "MIDDLE" of the car, so the sensitivity works equally from the front to the rear of the vehicle. Most shock sensors, as well, are designed to be mounted to a wiring harness too, so that makes the GEM area the perfect place to mount it, DEI or an alternative. Mines actually a 504D, but they are the same piece anyway. the difference being the 504D is what comes w/ the DEI alarm (where i scavenged mine from) and the 504M is just the shock sensor sold individually. I have a HP digi-cam that I purchased about 3-years ago, so that's as good as the pictures get. it's really easy, if you can handle putting it under the hood, this is no different, you just need a phillips screwdriver & some zip-ties

I've been having a nice conversation with DavidM3Blue about this issue of the DEI.

I've installed the DEI to the Tilt Sensor, this way 100% of the OEM functionality of the alarm is retained. I can open the trunk by the keyfob without disconnecting the alarm, and I can disable the tilt, motion and interior sensors by remote control by pressing the arm button twice.

The tilt sensor plug has five wires: the black wire with the blue stripe is the (-) trigger (wire #1), the red wire with the black stripe is the power lead (wire #3), the black with the red stripe is the ground (wire #5). Wire identification courtesy of Dirtboy.

Use 3M tap connectors for connection of the DEI to the tilt sensor. I attached the DEI to the same structural beam where the tilt sensor is located. All the car is covered from this location.

About the diodes:

Radio Shack sells the diodes, look for the model IN4004. You will need two of these diodes.

One will go in the trigger wire of the DEI (blue or green) and the other into the tilt sensor trigger wire (wire #1, black with blue stripe).

The diode have a grey strip or band across, make sure that this band is facing the sensor, i.e., the short black side of the diode should be facing the sensor, away from the wire going into the alarm brain. And more important, the two diodes should be placed so each sensor cannot "sense" the other.

This means that the tilt sensor's black/blue stripe wire has to be cut and the diode inserted above the tap of the DEI sensor trigger wire.

See this page for more information: http://www.the12volt.com/diodes/diodes.asp

To calibrate the sensor you will have to do it by try and error, activating the alarm and tapping the car until you get the sensitivity that you want. Remember that the DEI Blue wire is the only one that can be calibrated by turning the side screw. The Green wire sensitivity is set at the factory.

About connecting the DEI to the trunk pin:

(connecting the DEI to the trunk pin is acceptable)... as long as you realize that you no longer will be able to open the trunk with the keyfob while the alarm is activated if you use the hood trigger wire connected to a DEI.

If you open the trunk by keyfob while the alarm is activated, the alarm will be set off by the opening and closing of the trunk. This "motion" will trigger the motion sensor.

Normally this will not make the alarm to go off, because the alarm brain will disconnect the trunk pin trigger and the tilt and interior sensor for the time the trunk is open. The doors and the hood will continue to be protected, i.e., the hood pin will be active. Therefore, if the car moves -or enough vibration is caused- while you are opening the trunk, the alarm will go off.

Once the trunk is closed, inmediately the trunk pin will resume protection and 30 seconds later the tilt and interior motion sensors will be reactivated.

About the green (high sensitivity) vs. blue (low sensitivity) wire:

This is a common misunderstanding on this type of sensor. Check the back of your sensor, it will say:

Red - power

Black - ground

Green - warn (-) trigger

blue - alarm (-) trigger

What is happening is that this sensor is wired for aftermarket alarms -however, marketed for OEM alarms, go figure- , the ones with a warn input separated from ths alarm input. This is for light taps to the car, it just simply make the siren chirp two-three times depending of the brand of alarm. If these "taps" becomes numerous (i.e. three light taps in a row) or the "tap" becomes a hard knock, then the alarm goes off.

The BMW OEM alarm does not have any "warn" input...

To separate the "tap" from the "hard knock" is the purpose of the calibration screw. You see, you do not calibrate the "taps", you calibrate how hard the "hard knock" has to be to make the alarm go off. The sensor determines the sensitivity of the "tap" not the user.

Of course, this green wire can be considered the "high sensitivity" because it is always higher in sensitivity than the blue wire. Nevertheless, it does not imply that you can calibrate the green wire with the screw...

The only thing that I know is that I use the blue wire conected to the tilt sensor calibrated to the max, and when I hit the front bumper, side windows and rear bumper enough the alarm goes off. Something that did not happen the first time that I connected the sensor until I calibrated the screw to the max...

I hope that this information will help in your doubts...

Technic, Thanks for posting that!! I am sure others will find it helpful. I am going to try all 3 locations... hahaha.

Already have the hood pin one done, trunk is next and then behind the glove box.

Where do you get the 3M taps, they seem much better than the RadioShack ones, I was not happy with them.

wow, you guys are really hung up on this trunk thing. scheesh. you know, i don't think i've ever used my trunk button on the key. i just hit the button on the bottom of the trunk lid and poof, it pops open. just for reference, shock sensors don't like to be tied to metal, or something of structure. if you do use it in back, at least tie it to a harness the way it's supposed to be used. you will lose some adjustment at the front of the car however. this is why they are to be mounted in the middle of the vehicle, so the force is = from the front to the rear. i can set mine up so if a bird ****s on it on the front or rear it would prob. set off the alarm, and any where in between. any car audio shop should give you a hand full of 3M taps. the generic ones aren't worth beans.

Yeah the RadioShack ones gave me some trouble, but finally worked.

cls1000 -- I am going to do the glove box mount, as I like the idea of having it in the middle.

well, if you really want to be able to shut off the sensor guys, IE-using the tilt sensor, just locate the negative trip of the tilt sensor at the general entrance module instead of the hood pin wire, and all problems should be solved....

cls1000-- I was thinking that before, but which wire is it... hahahaha.

BTW... if I can get this information I will post a full DIY with all part numbers that are needed, etc.

Originally posted by DaveM3Blue
cls1000-- I was thinking that before, but which wire is it... hahahaha.

BTW... if I can get this information I will post a full DIY with all part numbers that are needed, etc.

well if you read back a couple posts, I guess it's a black wire w/ a blue tracer (- trip for the tilt) so locating this wire at the GEM should do the trick if that's the way you want it set up....

A DIY would be great! I just got my alarm activated, and as the stealership was going over it I was just standing there thinking to myself how insecure it is.

Originally posted by DaveM3Blue
cls1000-- I was thinking that before, but which wire is it... hahahaha.

BTW... if I can get this information I will post a full DIY with all part numbers that are needed, etc.

Had a question about this DIY. I originall had the shock sensor installed under the roof area in Black man's DIY

with DEI interface yellow going to ground.
Green wire going to general module control unit
red wire going to power
the tilt sensor was not used.

What wire in your DIY under the glovebox is the general module control unit?

Anyone still have pictures of the wires and shock sensor installed behind the glovebox? It's a mess of wires back there.

pics please!

pics would be nice...

Fresh pics much appreciated!!!!

I'm going to be taking my dash apart here shortly to make some minor mods so I'll be sure and take some new pics for everyone...