Factory horn trigger
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Factory horn trigger
I have an aftermarket electronic horn that is an amplifier with an external speaker. According to the manufacturer's diagram it has the following terminals:
[+ 12v]
[Ground]
[Two terminals to be shorted by external switch]
[Speaker cable + and -]
I would like to use the factory horn switch. I did some testing yesterday and verified that I can run the [+12v] and [Ground] off of the harness that connects to the factory horns under the bumper. With a jumper wire on the amplifier's switch terminals, this has the effect I wanted so I was going to hook it up like that. Then I got to thinking it would be easier to wire if I used the under-dash wiring from the factory horn switch. Using the above connections, how would I pull this off? Will the factory horn switch ground the amplifier's power circuit or is it more complicated than that?
TIA
[+ 12v]
[Ground]
[Two terminals to be shorted by external switch]
[Speaker cable + and -]
I would like to use the factory horn switch. I did some testing yesterday and verified that I can run the [+12v] and [Ground] off of the harness that connects to the factory horns under the bumper. With a jumper wire on the amplifier's switch terminals, this has the effect I wanted so I was going to hook it up like that. Then I got to thinking it would be easier to wire if I used the under-dash wiring from the factory horn switch. Using the above connections, how would I pull this off? Will the factory horn switch ground the amplifier's power circuit or is it more complicated than that?
TIA
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Joined: Jun 2002
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From: Under the flightpath of old ORD 22R
The horn switch on the steering wheel is a neg trigger to the horn relay.
Think of it this way, a relay coil ( like for driving lamps ) is usually triggered on the +12V of the coil, and the other side is attached to ground.
The horn relay is always attached to power, and the ground side is switched.
If you try to use the horn switch without the horn relay, the unit will need to power up, before working, and there might be a bit of a longer delay to this ( depending on the unit ), and give the delay reaction to the horn ( push the button, place your order and 2 seconds later you have noise
).
Ask the mfgr if it is ok to switch the ground side of the whole unit, rather then the +12v trigger terminal ( not shown on you quick list, is this the jumper ? )
Think of it this way, a relay coil ( like for driving lamps ) is usually triggered on the +12V of the coil, and the other side is attached to ground.
The horn relay is always attached to power, and the ground side is switched.
If you try to use the horn switch without the horn relay, the unit will need to power up, before working, and there might be a bit of a longer delay to this ( depending on the unit ), and give the delay reaction to the horn ( push the button, place your order and 2 seconds later you have noise
).Ask the mfgr if it is ok to switch the ground side of the whole unit, rather then the +12v trigger terminal ( not shown on you quick list, is this the jumper ? )
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From: So. California
[+ 12v]
[Ground]
[Two terminals to be shorted by external switch]
[Speaker cable + and -]
Sounds like they want you to use a switch to connect the two terminals you mentioned. That makes me think that one of the two terminals is a ground already. I would test those two terminals and use the factory ground to "short" the one of those that controls your aftermarket horn.
[Ground]
[Two terminals to be shorted by external switch]
[Speaker cable + and -]
Sounds like they want you to use a switch to connect the two terminals you mentioned. That makes me think that one of the two terminals is a ground already. I would test those two terminals and use the factory ground to "short" the one of those that controls your aftermarket horn.
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OK I *think* I get all of the above - and thanks a lot for the suggestions. When I tested the unit as I mentioned, I did this:
1. Disconnected the wiring harness at the factory horns (under passenger front fender) and connected + and - to the aftermarket amp's [+12v] and [Ground].
2. Jumped aftermarket amp's terminals that were meant to switch it.
3. Depressed factory horn switch & aftermarket horn honked instantly.
So, Sscully, I think it'll be fine to use the factory switch as the +12v on the amp unless you've got any reservations about it. In that case if I do understand you, I would connect the horn trigger to a relay as the negative trigger to supply the amp's [+12v]?
1. Disconnected the wiring harness at the factory horns (under passenger front fender) and connected + and - to the aftermarket amp's [+12v] and [Ground].
2. Jumped aftermarket amp's terminals that were meant to switch it.
3. Depressed factory horn switch & aftermarket horn honked instantly.
So, Sscully, I think it'll be fine to use the factory switch as the +12v on the amp unless you've got any reservations about it. In that case if I do understand you, I would connect the horn trigger to a relay as the negative trigger to supply the amp's [+12v]?
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Posts: 10,511
Likes: 10
From: Under the flightpath of old ORD 22R
Sounds good if there is no AMP delay, go with it.
Well...maybe I should ask, what is the load for the AMP ? I would imagine less then the horns..then again I should not guess.
If you are not beyond 80% of the horn fuse ( the one that feeds the horn relay ) you are good to go, no worries I would think.
Well...maybe I should ask, what is the load for the AMP ? I would imagine less then the horns..then again I should not guess.
If you are not beyond 80% of the horn fuse ( the one that feeds the horn relay ) you are good to go, no worries I would think.