Aftermarket alarm installation. - Page 4 - Benzworld.org - Mercedes-Benz Discussion Forum

**Jippi** · 02-16-2009, 01:14 PM

i have a working stock alarm for now, i built an interface module that replaces the stock one with an aftermarket one with out cutting up the wires. even tho i havent drove the car i went through 2 alarms. gonna buy the third soon its gonna be the same as the other car i have. right now i need to sit down and figure it out but on my installs i cant get the door trigger interface to work. when i open the door i get nothing.. no alarm no sound no nothing....

cypress188 · 02-16-2009, 03:53 PM

Don't know how you have it hooked up, but some info......more detail than you need I know, but others might find it usefull.

Door Switch:
a) When door is closed, switch = open
b) When door is opened, switch = closed
c) Switch with plastic housing on electrical pin is connected to "+12V"
d) Switch without plastic housing on electrical pin is connected to "GND"

Door:
a) Front doors (left & right) & Rear doors (left & right) are on separate circuits.

1) Therefore you need diodes to isolate, to keep them as separate circuits. You can use two diodes...1N4005 or similar will do.

2) If your alarm system have "negative" door pin sensing, than you connect one wire to "positive" terminal on front door switch, than the other end to "cathode" end of the first diode.

3) Now connect a wire to "positive" treminal on rear door switch, than connect the other end to "cathode" end of the second diode.

4) Now connect the "anode" of the first & second diodes together, than connect this to your alarm's "negative" door pin sensing input.

**Jippi** · 02-16-2009, 05:07 PM

dun worry i have it hooked up right i was testing and only had the front doors hooked up and it didnt work. i had it direct wired to the switch and the same thing. i havent really had the time to sit down and look at it. also for the diodes and all i would not use crimps. i would solder and heat wrap it. that would make it safe and less of a chance that it will short out.

message to all, personally i would not disclose that mounting location of where all the vital components of the alarm are located, under the mats, and behind the kick are cleaver places to hide it, but if someone really likes your car after seeing it up on the web or like what you have in it they can easily ripped out the alarm and steal it or dis arm it. i know its a big this help to anyone who wants an alarm installed but its not secure if someone with bad intentions can disarm it... this is all my opinion please do not get offended by what i said or be discouraged in posting othwer diy walk throughs.

Jippi

cypress188 · 02-16-2009, 05:26 PM

Quote:

Originally Posted by Jippi

dun worry i have it hooked up right i was testing and only had the front doors hooked up and it didnt work. i had it direct wired to the switch and the same thing. i havent really had the time to sit down and look at it. also for the diodes and all i would not use crimps. i would solder and heat wrap it. that would make it safe and less of a chance that it will short out.

message to all, personally i would not disclose that mounting location of where all the vital components of the alarm are located, under the mats, and behind the kick are cleaver places to hide it, but if someone really likes your car after seeing it up on the web or like what you have in it they can easily ripped out the alarm and steal it or dis arm it. i know its a big this help to anyone who wants an alarm installed but its not secure if someone with bad intentions can disarm it... this is all my opinion please do not get offended by what i said or be discouraged in posting othwer diy walk throughs.

Jippi

Totally agree, I have that uneasy feeling about it. Pic deleted, a second time....LOL. I was just going to post it for a few days, than delete it.

Sincity · 02-16-2009, 05:44 PM

That is true. But pretty much everyone knows is it usually under the dash somewhere.

**Jippi** · 02-16-2009, 05:54 PM

Quote:

Originally Posted by Sincity

That is true. But pretty much everyone knows is it usually under the dash somewhere.

yea, i also use multiple sources for the power wires.......

and i also know how to steal a certain sportline.....

mcimichell · 02-19-2009, 02:02 AM

A little update, that I think it might interest you, and some questions:
I checked with a multimeter the cables and I found out some things:

- Under the right front seat feet I only found a green and a blue wire, already interrupted, jointed and isolated, but I don't think it's the right ones, the green one wasn't going to the front passenger door;
- Under the rear seat, by the air pump, I saw the same thing, the connector to the pump with the 3 cables (blue RF door, green LF door, yellow trunk) 2 cables going to the vacuum pump, red + and brown - (as you can see on my previous post, picture #3), and 3 cables exiting from the vacuum cabling going to a connector, and after the connector interrupted, jointed and insulated, that go to the trunk actuator, so I thought it was better to intercept it there;

Picture #4

- I disconnected the connector. Of the 3 cables, the center is the yellow open/close command, the white-red is the + and the brown is the ground.
- I found out that shorting with a jumper cable the center yellow to ground it closes the doors, while shorting to the white-red it opens the doors. That's the only thing I want to do with my remote, actually!
- I don't know if taking the alimentation of the remote right from the white-red and brown..., that seem to be able to power it really good, it works. If in the future I want to hook the blinkers or the horn to it I'm aware that I need to move it to a more powerful line. But that's not my aim, for now!

Now the question to Jammerkiller or any of you that knows:
I also opened the iron hood in the front of the passenger seat, under the carpets, but it has nothing behind... where can I find all the horn and blinkers and power you were talking about in "Lots of possibilites with these cars. and all the wiring is in one spot!"?

I couldn't find the right spot! HELP!

**Jippi** · 02-19-2009, 06:17 AM

use the green wire, if you use the yellow one and you have your trunk double locked and you go and lock it with the remote it will automatically unlock.

chowbow · 02-19-2009, 10:19 AM

Whoa, you guys are hardcore... I went the n00btastic route when my driver's door key lock stopped working. The lock itself works but turning the key in the cylinder does nothing. It was cheaper to get keyless entry and while I can do audio installs, I've never done car alarms. I went with the n00b kit: Mercedes Benz Plug In Keyless Entry Upgrade - Home

Sincity · 02-19-2009, 10:34 AM

Mcimichell:

Perhaps you don't have a factory alarm on your vehicle? On our North American cars, we have the factory alarm and that is where most of us are tapping our alarm wires onto. If you look that Jammerkillers first two pictures, you will see 2 silver colored looking boxes. The larger one is the factory alarm.