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Discussion Starter · #1 ·
Adding this motion sensor to the OEM alarm is pretty easy once you find the correct trigger point, which in the 2007 GTI is the hood switch:


The switch has two wires, Pin #1 and Pin #2. Pin #1 is always grounded thus when hood is closed Pin #1 is floating. Hood opened make Pin #1 to close on Pin #2, which then triggers the OEM alarm once it is activated.
Therefore, any aftermarket sensor with a negative trigger can be connected to Pin #2:


To run the wires into the engine compartment I used a passage already made under the steering wheel bulkhead, to the left and above the brake pedal (only DSG, manual transmission GTI need to find another passage):

Use this Crutchfield wire "fisher" to pass the wire into the engine compartment, it will make your life easier from now on every time you need to pass a wire thru anywhere in the car:

The DEI motion sensor was installed right in front and below of the DSG lever for better sensitivity:

As explained before, there is no constant 12V wire anywhere in the GTI that is only active when the car is off, so I used a 5 pin relay to switch -in my particular case- the ACC line output of the PAC CAN steering wheel adapter as the trigger that will switch a constant 12V output to ON only when the car is off. This will be the motion sensor power input...
The relay/sensor wiring is like this:
Relay #86: ACC from PAC CAN or any ACC line found in the fuse box
Relay #85: Ground and Motion sensor Black wire
Relay #30: Constant 12V
Relay #87: Not used
Relay #87a: Motion sensor Red wire
Motion sensor Blue wire: Pin #2 of Hood switch plug
Motion sensor Green wire: not used in this application
http://www.the12volt.com/relays/relays.asp
A perfect installation will require an isolation diode between the motion sensor Blue wire and Pin #2; this will make the motion sensor electrically "invisible" to the hood switch and still work. However, because it is only ground I decided not to use it although I do not encourage it; it's up to you. For more information about blocking diodes check this link: http://www.the12volt.com/diodes/diodes.asp
This should be enough to install not only a motion detector but any other negative trigger sensor to the OEM alarm on the cheap: the price of this DEI 508D is around $5.00, add some wires, a diode, the relay and connectors and maybe you will spend $10.00 plus time... but it works like OEM. Close door, activate the alarm and any hard impact to the body or glass will trigger the alarm. Open door and the sensor is off as soon as the car is started and will remain off as long as the key is in the ignition. http://****************.com/smile/emthup.gif
For the ultimate protection it could be needed a second sensor in the trunk area to better protect the rear hatch. A front sensor can still protect the rear but the sensitivity will be borderline so it will require a bigger impact in the rear than in the front to trigger the alarm. Both sensors can be connected to the same trigger point, but two diodes would be needed to isolate one sensor trigger output from the other.
Good luck! http://****************.com/smile/emthup.gif



Modified by M3Tech at 6:47 PM 5-29-2007
 

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Re: (FUZE)

Just wire into the blinky led with the correct relay. Power makes it blink, so you are partially right. The only time it's active is when the alarm is active. Seems like a lot of extra routing of wires. Even the trigger.
Did you wire in a separate power switch so your battery doesn't die when it's parked for a few days?


Modified by syntrix at 8:10 PM 5-29-2007
 

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Discussion Starter · #5 ·
Re: (syntrix)

Quote, originally posted by syntrix »
Just wire into the blinky led with the correct relay. Power makes it blink, so you are partially right. The only time it's active is when the alarm is active. Seems like a lot of extra routing of wires. Even the trigger.
Did you wire in a separate power switch so your battery doesn't die when it's parked for a few days?

Modified by syntrix at 8:10 PM 5-29-2007

The DEI shock sensor consumes a very few mA, and the biggest drain is when it triggers by illuminating a LED for a few seconds, so it is a moot point when the OEM alarm is blasting. So it should not consume more mA than that blinky LED that you are talking about in a steady state. The battery should not even notice the extra drain...
 

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Discussion Starter · #6 ·
Re: (FUZE)

Quote, originally posted by FUZE »
Moderator: Can we get this added to the DIY?
OP: Thanks, and can you resize the pics for us non-cinema display folks

Sorry... I like big pictures, I cannot lie.
 

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Re: (FUZE)

Quote, originally posted by FUZE »

OP: Thanks, and can you resize the pics for us non-cinema display folks

or you can always get the "no pics" version (well, technically 1 pic), since my work blocks pb.
 

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Re: (M3Tech)

Quote, originally posted by M3Tech »

The DEI shock sensor consumes a very few mA, and the biggest drain is when it triggers by illuminating a LED for a few seconds, so it is a moot point when the OEM alarm is blasting. So it should not consume more mA than that blinky LED that you are talking about in a steady state. The battery should not even notice the extra drain...

That's right you are just doing a shock sensor, not a dei "radar" or "rf" sensor. That takes more power, but it can can detect someone putting their hand in the car http://****************.com/smile/emthup.gif
 

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Discussion Starter · #10 ·
Re: (syntrix)

Quote, originally posted by syntrix »

That's right you are just doing a shock sensor, not a dei "radar" or "rf" sensor. That takes more power, but it can can detect someone putting their hand in the car http://****************.com/smile/emthup.gif

That could be done too... http://****************.com/smile/emthup.gif
 

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Discussion Starter · #12 ·
Re: (T-DOG)

Quote, originally posted by T-DOG »
Any way to do this with out a pac can

Yes, use any signal that turns on with ignition (ACC), like the cigarette lighter jack. http://****************.com/smile/emthup.gif
 

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Discussion Starter · #14 ·
Re: (sasha18T)

Quote, originally posted by sasha18T »
Nice write up! Thanks! im doing this tommorow, and adding 2 Hella horns later...Is there any other parts needed besides the sensor?

A 5-pin relay...
 

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Discussion Starter · #16 ·
Re: (sasha18T)

Quote, originally posted by sasha18T »
crap, does radio shack have this?

Most probably you will find it in Pep Boys or any auto parts store.
You could try to find a 12V signal in your car that is hot only when the car is off, that way you do not need the relay or the ACC line.
 

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Discussion Starter · #18 ·
Re: (sasha18T)

Quote, originally posted by sasha18T »
would the wire going to the led lights in the door worK?? Think i will just buy the relay

It should... http://****************.com/smile/emthup.gif
 

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Re: (M3Tech)

Quote, originally posted by M3Tech »

Yes, use any signal that turns on with ignition (ACC), like the cigarette lighter jack. http://****************.com/smile/emthup.gif

Thanks going to try this later this week! http://****************.com/smile/emthup.gif
 
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