Where to get power from?
Printed From: the12volt.com
Forum Name: Car Security and Convenience
Forum Discription: Car Alarms, Keyless Entries, Remote Starters, Immobilizer Bypasses, Sensors, Door Locks, Window Modules, Heated Mirrors, Heated Seats, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=40125
Printed Date: May 14, 2025 at 4:49 PM
Topic: Where to get power from?
Posted By: p0rt21
Subject: Where to get power from?
Date Posted: October 01, 2004 at 7:36 PM
Hey
I just brought a new alarm to replace my old one. My old alarm has a wire leading to the ignition for positive.
Just wondering where the best place to get power from is?
Cheers
Replies:
Posted By: auex
Date Posted: October 01, 2004 at 8:59 PM
At the ignition harness or battery.
-------------
Certified Security Specialist
Always check info with a digital multimeter.
I promise to be good.
Tell Darwin I sent you.
I've been sick lately, sorry I won't be on much.
Posted By: vancouverbc
Date Posted: October 01, 2004 at 9:02 PM
I know you don't tap into your fuse box. That is the first place thief will look. At present i am just using the constant 12v+ that goes to ignition switch. I have heard that is ok. I think I might try finding something under the hood and bring it inside the car. It is pretty hard working under the dash. ------------- 1991 240sx
alarm=model 2620.web central door locking system
Posted By: p0rt21
Date Posted: October 02, 2004 at 2:35 AM
Just that if they tried hotwiring it they only need to pull it out. 
Posted By: vancouverbc
Date Posted: October 02, 2004 at 3:54 AM
won't they go for the wires at the ignition switch on the steering column. find the wire under the dash and put it high up under dash so they can't reach. my killer relays are going to be triggered by turning on radio. if they rip out alarm and rip power from killer relays , car won't start because killer relay is set up so that it needs power to connect the interrupted starter wires. i remove the face plate of radio when i leave car so no chance of them activating killer relay. i'm not using the killer relay that came with my alarm because if power is disrupted or alarm module is destroyed the relay closes and allows starter to work. i left remnants of the old alarm and killer relay to confuse them. i have these stupid wires tapping into the fuse box for old alarm. i just left it. hood lock is just as important plus a lock for the clutch pedal. the club is next to useless. ------------- 1991 240sx
alarm=model 2620.web central door locking system
Posted By: p0rt21
Date Posted: October 02, 2004 at 4:07 AM
What about having the car immobilize itself on arm with a latch. Then use the 2nd output/aux to delatch the relay?
Hey, thats a cool idea 
Posted By: vancouverbc
Date Posted: October 02, 2004 at 5:37 AM
yep, i might do it that way. have to think about it. i was thinking it might be better to have the killer relay completely independent of alarm module so not to have all my eggs in one basket. they could trace wires from alarm module to relay. ------------- 1991 240sx
alarm=model 2620.web central door locking system
Posted By: p0rt21
Date Posted: October 02, 2004 at 5:42 PM
Any one else have any input? :)
Posted By: vancouverbc
Date Posted: October 04, 2004 at 3:25 AM
"What about having the car immobilize itself on arm with a latch. Then use the 2nd output/aux to delatch the relay?" Ok, i don't really know what you mean. I don't know what second output/aux is. I tried various combo's of relays but it can't get the effect i want. ------------- 1991 240sx
alarm=model 2620.web central door locking system
Posted By: p0rt21
Date Posted: October 04, 2004 at 4:56 AM
Im not sure how you would do it but some alarms have an output for when the car is alarmed.
So when the car is alarmed it latches a relay (with a diode im guessing) then when you want to start the car you unarm it then use the aux/remotestart/trunk output to unlatch the relay. Not sure if it has been done before.
Anyone got any input on the idea? :)
Posted By: vancouverbc
Date Posted: October 04, 2004 at 1:28 PM
I need it to be normally open for arm and closed for unarmed so the output during arm is useless to me. trunk release output would not be sustained long enough for me to start car.
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1991 240sx
alarm=model 2620.web central door locking system
Posted By: snguyen
Date Posted: October 04, 2004 at 3:18 PM
In the end.. if the thief really want your vehicle that bad, they can tow it away. Alarms are mainly to slow the thief down. Time is their wrost enemy.
Posted By: p0rt21
Date Posted: October 04, 2004 at 4:27 PM
It would have to latch when you want to start it.
Alarm car - relay latches not allowing the car to start
Unarm car - relay doesn't change
Aux/trunk - relay unlatches
Just an idea. Not sure how hard it be. :)
Posted By: vancouverbc
Date Posted: October 05, 2004 at 1:44 AM
I don't know what auxillary is. I don't think i have it. I don't have any outputs i can time other than door locks. I guess the trunk release would work. I have to press the disarm button for at least 3 seconds and than an output goes to trunk or whereever. the problem would be if i stalled my car in traffic it would create safety issue because it might take too long to start. Thanks for your help. Sorry no one gave you a good answer about power. I like the ide of getting power from under the hood and bringing it in through the firewall. in conjunction with a hood lock this might be good. ------------- 1991 240sx
alarm=model 2620.web central door locking system
Posted By: p0rt21
Date Posted: October 06, 2004 at 4:01 AM
Anyone? Just want to know where the "pros" take there power from :)
Cheers
Posted By: mo12v
Date Posted: October 06, 2004 at 8:39 AM
Ignition Switch or Battery...............
Don't forget there are Alarms out there that when you hook up the Parking lights, a theif can just Break the Parking lite and short out the bulb to blow the fuse in the Alarm...........PooF.......no alarm.
Make sure your Parking light wire is fused
BELEIVE it OR NOT !!
Your ALARM is only as good as the Theif who doesn't know ------------- MO
Don't Learn from Others Mistakes
You Might Be the One That Knows.
Posted By: audiopro111
Date Posted: October 06, 2004 at 11:31 PM
ok if u don't want it to be messy and look professional but yet tough enough to steal there are many ways to dress the wiring it all depends on how creative u want to get, my suggestion to u as a installer is to dress u'r wiring (cover u'r wires) examples:electrical tape ,cloth tape or split loom ,basicly when u'r looking under the dash whatever u see your wires covered with that's what ur gonna cover your wires with the reason i say all this is because of my opinion it's allways been better for me and other installers i know to go to the ignition for power,the whole point is to confuse the thief a little more. I also was reading that u want to hook up a latch or output from your alarm to send a signal to interrupt a circuit ,don't forget that if your alarm offers an output for a starter kill relay it doesn't really mean u have to use it for your starter wire u could use it for an ignition wire or even your fuel pump, the starter wire is the first thing they go for,mind u this only applies if you are NOT installing a remote start with your alarm
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AudioPro111
Posted By: forbidden
Date Posted: October 07, 2004 at 3:47 PM
99% of the time, I'll go direct to the main wiring coming down the steering column. Connections here are made solidly with a good soldered connection that you will not have to worry about later on. mo12v had a good point, while more and more alarms now come with fused outputs for the park light circuit, if yours does not have a fuse on it, put one on it. If a thief can short circuit a bulb out, it may short the brain as well and then no alarm in the world is any good. ------------- Top Secret, I can tell you but then my wife will kill me.
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