Question about adding horn output

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=27934
Printed Date: May 31, 2024 at 3:14 AM

Topic: Question about adding horn output

Posted By: Zoomy821
Subject: Question about adding horn output
Date Posted: March 07, 2004 at 11:01 PM

Hi,
I just recently purchased an OEM GM alarm keyless entry system for my 97 Blazer. It has everything I want except for a horn output to sound the horn when you arm/disarm the alarm. I seen the digram on here where you use a relay and a flasher off the light flash output and I can do that pretty easily. But my question is this....why do you need a flasher? I mean, the brain sends a pulse signal to flash the lights, so couldn't you just use the relay and the same signal would pulse the relay? Is this a stupid question....or am I just missing something here? It will be no problem using a flasher and a relay because I purchased them both today at my local Advanced auto parts store, but I was just curious about this.

Replies:

Posted By: Bendog
Date Posted: March 08, 2004 at 12:05 AM

the purpose for the relay is to power both of them the headlight and horn because the ouput on the wire is not enough for both so the relay takes care of that. if you dont use the relay you will damage the device.

Posted By: JakeJ
Date Posted: March 08, 2004 at 1:04 AM

Just the relays should work. The parking light flash output should power a relay for lights and power a second relay for horn. The horn wire should be neg and the parking light should be pos. You need a relay for each because they need to be isolated from each other and are diferent polaritys.

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Wyoming 12volt Enthusiast

Posted By: Zoomy821
Date Posted: March 08, 2004 at 10:48 AM

Reply to Bendog....it shows in the diagram that the main wire from the brain is powering the siren....then you tap into that wire and wire in a relay.....then wire a flasher to the relay and then wire to the lights(in my case a horn)...I still don't see the purpose of the flasher if the brain is already sending a pulse signal to the lights and relay at the same time. I know...maybe because in the diagram they are going off of the siren output which is a constant power when activated...so i'm guessing that thats why you have to use the flasher...so the horn isn't blaring constantly. Huh...guess I answered my own question. Duh!
Well anyways...can I use the light flash output from the brain to power a relay to honk the horn? And if so...do I need a flasher for that? And do I only need one relay or two?

Posted By: derek123
Date Posted: March 08, 2004 at 12:44 PM

Try honking the horn for as long as the light flash out put is activated... remember two flashes on unlock.

I think you'll find the light flash pulses are too long to be used as horn honk pulses.

Perhaps the flasher relay shortens the length of the pulse going tot he horn ?

Posted By: sufferrar
Date Posted: March 08, 2004 at 1:18 PM

dreek123 is right . the flasher relay shortens the length of the pulse going to the horn . without the relay the horn pulse would be too disturbing when arming and disarming.

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