where to tap into 'alarm armed' wire

[SilverSaloon]

hi

i have a 1999 CLK.

I need to sense when the alarm is ARMED (or unarmed). Anyone know the best/easiest wire to tap into, nearest the radio as possible.

its so i can detect whether to switch something off ONLY when the alarm is armed....

thanks in advance!

derek

 

[Shude]

its so i can detect whether to switch something off ONLY when the alarm is armed...

You're loving those relays aren't you?

 

[SilverSaloon]

You're loving those relays aren't you?

hehe, i thought if i connect the relay up to the alarm it will cut the canbus wires when i lock the car, therefore the comand will switch off with the canbus sense before it cuts the power. should work a treat...

so, anyone know what wire i should splice into for the alarm.... it can either be sensing on, or off.... 12v

 

[SilverSaloon]

could i tap into the switch that flashes when the alarm is set on the dash? or would that be constantly switching live and off all the time???

anything else that i could tap into that indicates the alarm has been set?

 

[Shude]

anything else that i could tap into that indicates the alarm has been set?

there must be an alarm control box somewhere that draws a 12v permanent when the alarm is armed. I was going to suggest you take it from the internal sensors, but that might cause problems

 

[guydewdney]

<watches with interest>

Im not at home - but i have posted up several times a link to a russian site with wiring diagrams (i dont have the link here) - might be worth having a look through them to see if anything might spring to mind...

I would like the option of having the mirrors fold when the alarm is set..


edit - hmmmm
http://www.autolib.diakom.ru:8001/CAR/Mercedes-Benz/1997/S420/SYSTEM WIRING DIAGRAMS/6358.pdf

how about the 'hood switch' or bonnet switch? I wouldnt take much current from it though...

i have had a look through several years and models, S, E and C class - all have the same brown/red wire going to this switch - that is earthed on one side - and goes tot he control module the other. presumably it sends 12V to the switch, and if it gets earthed, it sets off the alarm. it might be the other way round though (i.e earthed all the time, and disconnecting it from earth sets off the alarm.)

Can you lock the car with the bonnet open? might just be a 'change of state' - so you could do away with the bonnet lock switch and use the wire - and just hope that noone goes to the hassle of ripping your bonnet up to get into your car (when they could just cut through your soft-top... )

 

[SilverSaloon]

after a bit of fiddling around thismorning before i drove to work, i figured out that the alarm tilt on/off switch on the dash only works when the key is out. also it only flashes when the alarm is set.

how do you remove the wood trim to get to the behind of these switches as i could attach the relay i have up to it and see how it acts when the alarm is set & unset etc quite easily once the wood is off.....

 

[Shude]

Can you lock the car with the bonnet open? might just be a 'change of state' - so you could do away with the bonnet lock switch and use the wire - and just hope that noone goes to the hassle of ripping your bonnet up to get into your car (when they could just cut through your soft-top... )

Yes, the car locks with the bonnet open . Last night while adding a drop of oil and filling up the washer reserviour (hope I got them the right way around ) I had to leave the car while I went into the garage, so I locked it with the bonnet open, seemed fine.

EDIT: just realised that it might monitor the position of the bonnet regardless of alarm!

 

[SilverSaloon]

Yes, the car locks with the bonnet open . Last night while adding a drop of oil and filling up the washer reserviour (hope I got them the right way around ) I had to leave the car while I went into the garage, so I locked it with the bonnet open, seemed fine.

EDIT: just realised that it might monitor the position of the bonnet regardless of alarm!

does it lock the boot when the engine is running tho, as i am tapping into the wire to enable the canbus wires it needs to only cut the canbus wires when you are out of the car and the car is standing.

 

[SilverSaloon]

tried the alarm switch - it didnt work

 

[jimmy]

The bonnet and door switches are switching the negative from the bodywork, when they open they complete the negative circuit and trigger the alarm, so not much good for what you want.

Even if you find the alarm control unit, (under the passenger foot plate usually) the wires should not be colour coded, well on Fords at least there is just a mass of black wires going into it. Makes it harder for thieves to disable the alarm. However you can identify the wires by pin location.