bpr0422

Okay this isn't my original idea, I found this somewhere - i forget where - last year...

Its a fuel cut off switch that works with your alarm's door lock interface.

The circuit defaults to ARMED (Fuel cut) when the power has been removed.

They way it works is when the alarm LOCKS your doors the fuel is cut, and when the alarm UNLOCKS your doors the fuel is restored.

The problem with this circuit is that it still cuts your fuel when you want to turn on the car yourself - this is only if your alarm locks your doors when you start the car...

But I added a relay so that you can still use the alarm's lock-when-on interface...



Relay 1: Isolates the Circuit from being armed (fuel cut) when the car is on
Relay 2: The DISARM relay, this relay restores the fuel
Relay 3: The ARM relay, this relay when grounded cuts the fuel
Relay 4: Does the actual cutting of the fuel circuit.

If you have power locks on your car, you MUST isolate this circuit from the stock power lock's circuit!!!!!!!!!!

Use blocking diodes with the stripe on the same side as the alarm box!!! If you don't the thief can just disarm the system with the lock and unlock switches!!!


I recommend that you change the order of how you wire the relays to make it more confusing for thieves, cause all cut offs are easily bypassed by jumping the cut off points with a piece of metal...

I'm going to wire this to my ignition but you can also wire it to your ACC or AMP on lead from your HU.

You can also eliminate the first relay if you don't have the lock when on feature or you can use two push buttons to control the switch.

You can also add an anti hijacking button, just wire it to ground the Lock Ground wire before the isolating relay. Just push the button to cut the fuel!

You think of a place to hide this, it isn't that small.. but can easily be loomed and hidden

This circuit can be simplified - but the way it is wired now makes it so that when you valet park your car the valet guy will still be able to start your car without making you walk to your car...

e.g.

If you wire the Constant battery to your ignition, the system will always arm when you turn off your car... and only disarm after you put the key in the ON position and then hit unlock button on your alarm's keyfob


Modified by bpr0422 at 7:10 PM 5/22/2007


Modified by bpr0422 at 7:11 PM 5/22/2007

wrx-killer-Sti-eater

iTrader: (1)

To much work and extra parts that I could do with just one relay. Extra money spent on relays. Time to wire it up. Hopefully a relay does not go out in time. Hiding all that. And say if the theif unlock your door with a coat hanger.

bpr0422

You are supposed to wire it so that it only works with the alarm's lock and unlock leads..

also u can separate the relays... yeah its alot of work.. and other things can fail.. but...

did i mention i had extra relays lying around...

wrx-killer-Sti-eater

iTrader: (1)

After looking it over. It will work but just alot of extra work.

bpr0422

its alot of work.. sorta.. not really cause you can do all if it sitting at a desk with a soldering iron.. then it is just cutting and tapping the unit in.. unless ur going to separate all the relays from each other.. which is better i guesss. but a pita.

the advantage to this is that you don't have a visible physical switch that disarms the system - cause a thief could get lucky some day and find ur switch...

its just an extra layer... and can act as your anti hijack switch...

also the unit can be placed away from the alarm brain, all it needs access to is the alarm brain's lock/unlock leads, so if they find it.. ur alarm's cut off is still intact, or if they find your alarm this unit still works.

you could also use hidden magnetic switches.. on this and not have to be able to leave the magnet in place.. just swipe the magnet by the spot and the system is disarmed or armed..


Modified by bpr0422 at 8:21 PM 5/22/2007

suspendedHatch

Why not hook it up to the alarm's ground-when-armed output as opposed to the door locks? You've already stated at least two reasons why NOT to control it with the door locks.

perseverance

i've got a much better way of doing it... i drew out the circuit at my job. i don't want to post it tho. but it works great. fuel pump is always hooked up unless they cut power to the alarm. that's all i'll say. i'll probably install it tomorrow seeing that last night someone broke into my boy's turbo hatch. they didn't steal it but came damn close. good thing i did his alarm. if i do do it tho... i'll do a write up..

bpr0422

actually... i forgot about that..

thats what happens when u think when ur brain is fried...



if u hook it up to your ground when armed... it eliminates the need for the extra relay...

..

i feel stupid now...

-------------

you could then wire a relay N/C to invert the ground when armed near the brain to make a ground when disarmed.. and use that line to ground a N/O relay near the main relay...

would be a lot simpler.

nsxxtreme

Can I ask why?

This does the same thing your starter kill does if you set it to active. If you want to control ignition just add a sense wire to the starter kill relay.

suspendedHatch

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by perseverance &raquo;</TD></TR><TR><TD CLASS="quote">i've got a much better way of doing it... i drew out the circuit at my job. i don't want to post it tho. but it works great. fuel pump is always hooked up unless they cut power to the alarm. that's all i'll say. i'll probably install it tomorrow seeing that last night someone broke into my boy's turbo hatch. they didn't steal it but came damn close. good thing i did his alarm. if i do do it tho... i'll do a write up.. </TD></TR></TABLE>

I'd be interested to hear how you did that w/out having the relay always energized.

nsxxtreme

There are much better ways to do this kind of stuff then with relays.

The only thing a relay should be used for is for switching on a high current source.
It would be soooooo much easy and use so much less power using digital logic.

bpr0422

actually

truth is, i'm going to use this complex relay contraption on the door locks because I am afraid that the thief will be able to disarm my alarm using the disarm sequence that all dei units have...

cause switching the ignition to on is as easy as taking out two screws...

suspendedHatch

Two screws?! Just connect a wire from the battery to the plug on the distributer. 0 screws.

wrx-killer-Sti-eater

iTrader: (1)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by bpr0422 &raquo;</TD></TR><TR><TD CLASS="quote">actually

truth is, i'm going to use this complex relay contraption on the door locks because I am afraid that the thief will be able to disarm my alarm using the disarm sequence that all dei units have... </TD></TR></TABLE>


And what would that be?

bpr0422

straight from the viper user manual:

"disarming without a transmitter"

classified......

who knows who reads this.....

and the guys who broke into my car looked like they were searching for the button...