Homemade alarm system?

Anyone out there ever made an alarm system for their Jeep before?

I've been pondering the idea of hooking up a siren in the engine bay to a switch with a 5second delay resistor added, the switch in my case would be the fog light switch (since I don't have them anymore) and the switch would turn on a motion sensor.

Basically I'm thinking I'd turn the fog light switch to on, to arm the system, and I have 5 seconds to lock/close the door. Then if anyone were to break into the Jeep or open a door with the alarm system on, after 5 seconds of movement (using the motion sensor inside the key less entry box on my '89) the alarm will sounds, until there is 5 seconds of no movement...in which it would turn off. And since the fog light switch is OEM, it's unlikely a hijacker would bother to try turning that switch off.

It all sounds pretty do-able to me. But I could be crazy.

~Scott

P.S. I'm just thinking this up as a project to do when its raining or something, not because my Jeep is at high risk of being stolen...but rather for amusement and preparation. Plus I already have a siren, wire, and sensor.

your neighbors are going to love you.


i am not saying it won't work, but the alarm companies have lots of research into what works and what won't.

is it a siren, or a PA speaker? i used to have my PA horn hooked up to my CB, it was great talking to people in traffic

tomcat said:

your neighbors are going to love you.


i am not saying it won't work, but the alarm companies have lots of research into what works and what won't.

is it a siren, or a PA speaker? i used to have my PA horn hooked up to my CB, it was great talking to people in traffic

Click to expand...

Yeah the more I think about it, the more I realize the sensor would have to be really weak.

It's a siren, but I do plan to get a PA speaker for my CB...I had a friend who had one, and it was awesome being able to call people idiots and them actually hearing you...but not knowing where it was coming from. :roflmao:

~Scott

I am a 12V installer, and really see no reason this couldn't work quite well.

Yes, alarm manufacutrers do a lot of research, but they are making a product that has to work in about any car or truck. They also add many features that are not required to secure your Jeep, and are simply for convience. For example, the remote control and keyless entry. That stuff is nice, heck I have a remote start on mine, but it's not needed if security is your only goal.

With it all set up right, what you're thinking of doing would be just as, if not more, effective as any high dollar alarm system. Heck, for the most part, a blinking LED on the dash will be just as much of a deterrent as any alarm.

I stole this but.....

Get a red button that says start on it and hook it up to a siren or Horn and place it on the dash. That should alert you or anyone near that someone is in the car.

Cheap Alarm...........that's half a joke half a good idea.

It'll probably take a lot of testing/adjusting to get it so the motion detector doesn't see too much thru the windows. You don't want it going off for no reason in the parking lot because somebody is getting in/out of their car or whatever.

kujito said:

It'll probably take a lot of testing/adjusting to get it so the motion detector doesn't see too much thru the windows. You don't want it going off for no reason in the parking lot because somebody is getting in/out of their car or whatever.

Click to expand...

That's why I was thinking a 5second resistor would be good. It's unlikely someone would be spending 5 seconds around my car moving...and worst case it would warn them not to hit my rig with their door.

~Scott

Well, it won't safeguard property inside the car but here's my old man's car theft solution:
Find a place that is real out of the way, like between the seat and the center console, and mount two switches there. Both pushbutton switches are wired to relays in series or in parallel, but the gist of it is, both switches have to be pushed to open the relays allowing power to your fuel pump. Or just one switch - whatever.
Don't know the hidden switch? No fuel to engine. Car isn't going anywhere.
He also did it, on another car, such that a garage door opener needs to be hit to turn on the fuel pump. You could do the same with a keyless entry fob, I"m sure.
Again - won't make any noise, won't protect valuables in the car, but it's a damn sight more effective than a siren at keeping the Jeep from wandering off. No fuel, no worky.

kujito said:

It'll probably take a lot of testing/adjusting to get it so the motion detector doesn't see too much thru the windows. You don't want it going off for no reason in the parking lot because somebody is getting in/out of their car or whatever.

Click to expand...

It takes a good amout of setup using an alarm with the motion sensor too. Especially since most are dual zone sensors. The dual zone sets about a 4ft warning perimeter around the car, that will set off a warning chirp if entered. Then if you break into the 2nd zone, it sets off a full alarm.
You may be able to do something similar using a soft chirp siren. They send out warning chirps for a couple seconds before going into full alarm. This may help let people know not to mess with it, before your neighbours wake up
Also, to keep from disturbing the peace, just use a low current 12V lamp on the siren wire during setup.

yossarian19 said:

Well, it won't safeguard property inside the car but here's my old man's car theft solution:
Find a place that is real out of the way, like between the seat and the center console, and mount two switches there. Both pushbutton switches are wired to relays in series or in parallel, but the gist of it is, both switches have to be pushed to open the relays allowing power to your fuel pump. Or just one switch - whatever.
Don't know the hidden switch? No fuel to engine. Car isn't going anywhere.
He also did it, on another car, such that a garage door opener needs to be hit to turn on the fuel pump. You could do the same with a keyless entry fob, I"m sure.
Again - won't make any noise, won't protect valuables in the car, but it's a damn sight more effective than a siren at keeping the Jeep from wandering off. No fuel, no worky.

Click to expand...

I agree, this is a good way to keep someone from stealing your rig! I have ran into several of these kill switches, and people can sure get pretty clever with the locations! I've seen them as; hazard switches, fake cigarette lighters, cruise control buttons, toggles hidden under the dash, etc...
You can also tie into the starter wire. I've seen cars wired so the headlights had to be on, or you had to turn the radio on before it would start. However, the fuel cutoff is more effective. It's not too hard to bypass the starter circuit, but a well hidden interruption in the fuel circuit is another story.