View Full Version : DIY: Poor Mans Alarm

08-15-2010, 03:38 PM
This is a DIY I made to make a poor man's alarm system for under the hood. Basically, if an intruder lifts the hood the horn will go off. I did this because my car was broken into not long ago...

If you want your horn to blow when someone pops your hood when you arm it, proceed...
Supplies You Need:
_Pushbutton Normally-Closed Momentary Switch (part number 275-1548 @ radio shack)
_Open/Close Switch (whatever style you prefer)
_Wire/Wire Splitters/Electrical Tape
_Wire Feeder or Wire Hanger

Total cost of everything should be under $10

How it works: There are two switches, the first is located inside the car (I put mine on the bottom left of my dash). It will arm & disarm the hood switch. The hood switch is located inside the hood and will go on if the hood is open and off if the hood is shut. If both switches are ON, it completes a circuit to the horn and the horn will sound. If the hood is open but the indoor switch is disarmed, no alarm will sound.


1) Remove the plastic pieces surrounding the steering wheel.

2) Remove the white connector just above the steering wheel. The connector has an ORANGE wire all the way to the RIGHT if you are facing it from the front. This wire is for your horn.

3) Splint the wire and take a new wire to connect the two. Wrap with electrical tape. Run your new wire down behind all panels to where you'd like your switch to be.

4) Cut and connect the wire to one side of the switch. All switches are different, follow the directions so that the switch is installed properly.

5) Connect the other end of the switch to a new wire. Run this wire through your door jam. ::If you remove the lower sleeve pocket on the bottom left of your front, you'll access the rubber boot to the jam easily. Run the wire through this boot and out on the other side (bottom of picture).
Run the same wire through a little gap in the door jam to lead to the hood of the car. (top of the picture).

6) Install the push button switch in the hood. If you buy the pushbutton switches from RadioShack, you will notice they fit greatly into one of the side holes of the hood. Here is mine installed:
NOTE! The PushButton alone is not high enough to make contact with your hood. I used a plastic wire connector laying around the garage that fit greatly around the button & superglued. It is at a height that pushes the button COMPLETELY when the hood shut and locked.

7) Connect the wire you ran from the door jam to the Push Button switch.

8) Run another wire from your battery ground (or another ground source) to the push button switch. You're done! When your switch inside is set to arm (on), your horn will go off if someone tries to pop open your hood.

My switch inside my dash:

08-15-2010, 04:19 PM
nice i would have opted for a smaller stealth switch. but none the less nice

08-15-2010, 05:36 PM
very cool alarm setup!

08-15-2010, 06:08 PM
nice i would have opted for a smaller stealth switch. but none the less nice

very cool alarm setup!
thanks! yea i might hide it another time once i get used to arming my car with it. & i also have it so the switch inside doesn't light up. what i was more focused on was hiding all the wires.

08-15-2010, 08:41 PM
yeah my cheap ass opted for diy fuel pump, crank and clutch starter switch. sometime i forget its on

08-15-2010, 08:44 PM
awesome write up. i prolly won't get around to doing it cause my car is garage kept, but good write up indeed sir!

05-28-2011, 09:09 PM
make a friend and best buy. best viper alarm goes for under $150+$100 for install.