Horn relay question

[valleyman]

I am bound and determined to hook up the three trumpet horn set I took out of a '68 El Dorado in place of the weak sister pair of OEM horns that came on the MM. The problem is that the Cadillac horns blow the 15 amp fuse in the horn circuit. So, I've been looking in my wiring diagram and I plan on putting in a 20 or 25 amp fuse in its place, whichever is the lowest rating that the Cadillac horns will function through. Does anyone know if the horn relay can take the added amps? If it can't, does anyone know if Ford makes a horn relay that is rated for more amps and that will fit in the five-prong slot in the battery junction box where the OEM relay is now (it's connector #1006)?

I plan on putting an in-line 15 amp fuse in the part of the circuit that is downstream of the horn relay: that continuing circuit contains the main lighting module, the cruise control and some airbag sensors, and Ford probably has a reason for protecting them with a 15 amp fuse. Since my knowledge of electricity is pretty much limited to knowing only that it can hurt you, can anybody help me out here or warn me off before I do irremedial damage to things I shouldn't be messing with?

[RF Overlord]

I plan on putting in a 20 or 25 amp fuse in its place

Don't do it!

It's not only the horn relay that's of concern here, it's the gauge (size) of the wiring. If it originally had a 15 amp fuse, then the wiring in that circuit is only suitable for that amperage, no more. If you put in a bigger fuse, you risk heating the wire, melting the insulation, etc. My suggestion is to run a new feed from the power distribution box to the horn relay input, and also a new wire from the horn relay output to the new horn. That way, you can install the appropriate gauge wiring and fuse suitable for the new horn, while leaving the old wiring in place, should you ever want to restore it.

BTW, a 20-amp circuit should have at least #12 wire.

[martyo]

As much as it pains me, I am inclined to say that I agree with RF ^^^^

I need to go take a nap now -- I am in agony.

[duhtroll]

I want the "HUUUNNH" from a semi. How much for that? Do I need a new wiring setup also?

180 decibels ought to be sufficient. Then the old ladies in the left lane going 14 mph can hear me.

-A

[valleyman]

. My suggestion is to run a new feed from the power distribution box to the horn relay input, and also a new wire from the horn relay output to the new horn. That way, you can install the appropriate gauge wiring and fuse suitable for the new horn, while leaving the old wiring in place, should you ever want to restore it.

BTW, a 20-amp circuit should have at least #12 wire.[/QUOTE]




You think the horn relay can handle the extra load though, right?

[RF Overlord]

You think the horn relay can handle the extra load though, right?

Not necessarily...my point is that it's not ONLY the horn relay you should be concerned about.

The good news is that horn relays are relatively cheap compared to replacing a burnt-up wiring harness...

You might want to consult with a professional alarm installer, or a shop that does stretch limos or conversion vans...

[gja]

While RF is correct, he is failing to point out the BEST way.
Take the lead from the current horn and use it to fire off a NEW relay fed DIRECTLY from the battery.
This leaves all your stock wires intact.
Put a fuse inline and supply a good ground.
Size the relay according to the load you are trying to run, this would generally be a relay with about 10% more capacity than the fuse the manufacturer of the device you are going to power specifies.
DO NOT TAKE SHORT CUTS!
DO NOT CUT/TAP/STRIP INTO YOU FACTORY HARNESS!
DO NOT LEAVE IT ALL HANGING LOOSELY.
Electrical work should always be neat and easily traceable.
That is the earmark of a good job.
Oh, and color-code your work.
Use red wire for all positive leads and black for ground.

[valleyman]

Thanks, guys. And gja, where do I get such a relay? Like at a Radio Shack or electronics-type store? Are there any magic words that I should use so they know what I'm asking for, so that I can minimize my exposure to strangers as a complete electrical idiot?

[gja]

You can get them at any good aftermarket auto place.
Don't buy a relay that is not designed specifically for auto use.
Ones that are include a fair amount of weather-tolerance, if not even weathertightness.
A good relay will have a mounting tab with a hole in it to make it easy to mount. That screw, if large enough, can even be your grounding point for the relay.

[David Morton]

I want the "HUUUNNH" from a semi. How much for that? Do I need a new wiring setup also?

180 decibels ought to be sufficient. Then the old ladies in the left lane going 14 mph can hear me.

-AYou'll need an onboard air compressor for that one.

A friend of mine once found one of those multi-trumpet diesel-electric locomotive horn assemblies at a pawn shop, it used compressed air and weighed about fifty pounds. Now that would turn some heads!:party:

[valleyman]

While RF is correct, he is failing to point out the BEST way.
Take the lead from the current horn and use it to fire off a NEW relay fed DIRECTLY from the battery.
This leaves all your stock wires intact.
Put a fuse inline and supply a good ground.
Size the relay according to the load you are trying to run, this would generally be a relay with about 10% more capacity than the fuse the manufacturer of the device you are going to power specifies.
DO NOT TAKE SHORT CUTS!
DO NOT CUT/TAP/STRIP INTO YOU FACTORY HARNESS!
DO NOT LEAVE IT ALL HANGING LOOSELY.
Electrical work should always be neat and easily traceable.
That is the earmark of a good job.
Oh, and color-code your work.
Use red wire for all positive leads and black for ground.

gja -- I still need a little help here, please. I got a three-prong horn relay from a parts store. One lead to the horns, one lead to the battery and one lead to the horn button (switch) is how it is designed to work. Is this the right type of relay for me to use? I already hooked it up independently from the MM's wire harness and it works just fine. What I can't figure out is which wire from the connector at the MM's horns, the ground or the hot one, to connect to the new relay, and where to connect it to the new relay. Does the metal body of the relay itself have to be grounded? It doesn't look like it has to. Am I going in the right direction here or do I need a four or five prong relay. They had those too at the store but I figured I'd start with the simplest.

Any help, from anybody, would be mucho appreciated.

[jaywish]

I could be wrong here but I guess with a 3 contact relay (that does not get grounded) you have

1) from battery- hot
2) from switch (horn button) -ground
3) to horn, switched power out- hot

When you tested it is that how it worked ?

If that is how it worked, then you connect the hot switched output to the horn hot terminal.

A suggestion, I'd put the fuse right at the battery. Unless you are taking power from the fuse panel somewhere. In that case put the fuse right at your tap. The earlier the fuse the more of the wires are protected.

If this is not how you tested it, please post how you tested it.

Jay

[Mike Poore]

As one who has run as much as 85 amps to a mobile HF ham rig/amplifier, you need to run BOTH your pos. and neg. wires directly to the battery. Put fuses in line on both wires, and as close to the battery terminals as possible. You don't want a long wire connected directly to the battery that could get shorted in an accident.

[gja]

I just saw this so here goes....

1. Mike is correct. We are both Amateur radio ops with high current equipment, so believe us when we say to use home runs to the battery for the feed side of the load.

2. A 3 contact relay is quite enough.
1 contact goes to the battery positive.
1 to the "load" (horn/whatever)
The 3rd goes to your present horns.

Remember that since you are using the output that normally powers your horns to only trip the relay it is now isolated from the high current load via the relay.

Most all horns connect via a "spade" lug or such, so you should be able to find a mating end to it in a good car part store. You can crimp it onto a length of wire with an inline fuse for protection and use some wireties to keep it all neat. This means you don't have to touch your stock harness in any way.

[jaywish]

I just saw this so here goes....

1. Mike is correct. We are both Amateur radio ops with high current equipment, so believe us when we say to use home runs to the battery for the feed side of the load.

2. A 3 contact relay is quite enough.
1 contact goes to the battery positive.
1 to the "load" (horn/whatever)
The 3rd goes to your present horns.

Remember that since you are using the output that normally powers your horns to only trip the relay it is now isolated from the high current load via the relay.

...


Hi,

I'm curious about what you say here. In valleyman's post he said he tested the relay without grounding the case. If you are using the present power leads to the horns to actuate the new relay, where does the ground come in to complete the circut and throw the contact in the relay?

Thanks
Jay

[gja]

The 3 terminal relay MUST be grounded.....
A 3 terminal relay will have a grounding/mounting tab on it.
Those are preferable to the plastic cased 4 terminal relays commonly used for foglamps and such. The reason I say it is preferable is the strong tab provides a good grounding point for the RELAY (NOT the LOAD).

Instead of it being held in place by the wiring, it holds the wiring in place.
If you can't find a metal cased,sealed unit, then a 4 contact sealed/plastic will do.

[jaywish]

The 3 terminal relay MUST be grounded.....
A 3 terminal relay will have a grounding/mounting tab on it.
Those are preferable to the plastic cased 4 terminal relays commonly used for foglamps and such. The reason I say it is preferable is the strong tab provides a good grounding point for the RELAY (NOT the LOAD).

Instead of it being held in place by the wiring, it holds the wiring in place.
If you can't find a metal cased,sealed unit, then a 4 contact sealed/plastic will do.

Agreed, this makes scense. Still I'm not clear about Valleyman's last post which, from my reading, indicated he checked the relay function without grounding the case.

Jay

[valleyman]

:bows: First, just let me say, Oh Lord, thank you for having the MM members have mercy on my ignorant butt before I blew out something expensive.

So, if I'm reading gja and jaywish correctly my new three-prong relay gets 1)its hot terminal connected to the battery (just like it's supposed to), 2) its horn terminal connected to the Caddy horns (just like it's supposed to), 3) but its terminal that is designed to be connected to the horn button on a steering wheel is instead connected to one of the two wires that I've disconnected from my current horns. And the one of those two disconnected wires that I should use is the one that comes from the OEM horn relay (the "hot" ) one, and not the one that just runs to a ground on the frame. Right?

And I will mount the metal case on a grounding surface like you suggested, gja. That's why I bought a relay with a metal case with a mounting tab built into the case. And I'm sorry about the confusion in my post: I tested the relay after I bought it with it just sitting on the work bench. I had one prong connected to the Caddy horns, which I grounded to the MM with a jumper cable, one prong to the MM's battery, and the third prong, which I was pretty sure was supposed to go to a grounding type horn switch, I just grounded to the battery with another jumper cable. (The relay itself wasn't grounded, it was just laying on the bench.) The horns blew like crazy, so I knew I had figured out which prong was supposed to do what since there were no directions or a schematic of any kind that came with the new relay.

Anyhow, time permitting this week I'll get them hooked up. Thanks all.

[Krytin]

I'm not touching the wiring end of this w/out seeing it but a good source for heavy duty relays/holders and fuses/holders would be a truck parts supply house. Just my $.02.

[jakdad]

I want the "HUUUNNH" from a semi. How much for that? Do I need a new wiring setup also?

180 decibels ought to be sufficient. Then the old ladies in the left lane going 14 mph can hear me.

-A No worry on the wiring. Those are air operated. Just mount your air compressor,tank and horns and you're in business!
:lol: :lol: :lol:

[jaywish]

:

And I will mount the metal case on a grounding surface like you suggested, gja. ... And I'm sorry about the confusion in my post: I tested the relay after I bought it with it just sitting on the work bench. I had one prong connected to the Caddy horns, which I grounded to the MM with a jumper cable, one prong to the MM's battery, and the third prong, which I was pretty sure was supposed to go to a grounding type horn switch, I just grounded to the battery with another jumper cable. (The relay itself wasn't grounded, it was just laying on the bench.) The horns blew like crazy, so I knew I had figured out which prong was supposed to do what since there were no directions or a schematic of any kind that came with the new relay. ...




Valleyman,

If this is how you tested the relay, by adding ground on the third contact to blow the horns, then that is the way this particular relay works. NOT the way we said just above by using the hot lead to the old horns.

Refer to my 1st post in this case.

:

1) from battery- hot
2) from switch (horn button) -ground
3) to horn, switched power out- hot



Based on this relay being activated by a ground lead you have two choices.

1) get a different relay that is activated with a hot lead and you can mount it right by the old horn wires.

2) you can use this relay but you have to take the ground connection for the new relay from the existing ground lead from the steering wheel horn switch. Probably right at the connector for the old horn relay would be the easiest spot. Remove the old relay, plug in a spade connector and run the wire to the new relay.

I'll look at the Marauder wire diagrams tonight unless anyone else has them handy and can verify this?

Jay

[jaywish]

Well I finally checked the wire diagrams.

It is as usual, the horn relay is actuated by completing a ground through the steering wheel buttons.

The stock relay is a 4 connector. the 4th connection is fed power from the same fuse which powers the horn, It's just jumped over to the 4th pin.

The relay is located in the "Power Junction Box"(PJB) which is directly behind the battery.

The relay is # C1006. If you stand directly in front of the battery and front bumper and look in the open PJB you will see 4 light tan relays in a vertical row. It is the only completely filled vertical row. The horn relay is the lowest one (closest to the front of car). I believe the relay numbers are marked on the lid of the PJB but they were too faint for me. Remove the relay and check by turning car on and trying the horn. If you pulled the correct relay it won't blow.

Judging by the book the relay pin should be #2 which plugs into PJB socket is # 1. You can also identify the correct socket by.
1)check for voltage with key on - there should be none on two of the four sockets.
2) check for ground on the 2 no-voltage sockets when horn button is pushed. The one with ground is the one you want.
It is 50/50 which none powered socket is the correct one and you could always try them sequentially with the new horns wired in.

Keep out the original relay and you can plug into the horn button socket right in the PJB and convienently run a wire which will actuate your aftermarket relay.

I can't say what ford would say about the warranty on your electrical system :cowboy: but you would only be using the existing button and wireing to trip a different relay, big woop. If you ever want to return to stock just remove your custom hardware and plug in the stock relay.

I guess if you want to be bullet proof you could put a 15A fuse in the ground lead going between the PCM and your new relay. I think the odds of the wireing leading to you steering wheel ever getting 20A from the relay is very slim but this second fuse would virtually preclude this possibility.

This should all work if you have purchased a ground actuated relay, as you have indicated, and you run a fused home run hot from battery to relay. In the sizes specified earlier in the thread. Remember the 20A fuse should be right off the battery.

Take Care,
and you better not sneak up behind me and blow that thing.

Jay

[Captain Steve]

I want the "HUUUNNH" from a semi. How much for that? Do I need a new wiring setup also?

180 decibels ought to be sufficient. Then the old ladies in the left lane going 14 mph can hear me.

-A
What you really want is the air horn from a tug boat. Just get yourself a SCUBA tank, a regulator (to go from 3000psi in the tank to 150psi), some diver hoses, and a valve.

Push 150psi through an air horn and people in front of you will think it's Judgement day.:burn:

[ahess77]

No worry on the wiring. Those are air operated. Just mount your air compressor,tank and horns and you're in business!
:lol: :lol: :lol:

Did you guys forget, you already have an air compressor on board (rear air suspension)

OK, maybe not quite enough pressure for those air horns.

[jakdad]

Did you guys forget, you already have an air compressor on board (rear air suspension)

OK, maybe not quite enough pressure for those air horns.
That would be awesome! Toot your horn and the back of the car goes to the ground!

:rofl: :rofl:

[valleyman]

Jaywish -- Thank you, thank you.

[jaywish]

What you really want is the air horn from a tug boat. Just get yourself a SCUBA tank, a regulator (to go from 3000psi in the tank to 150psi), some diver hoses, and a valve.

Push 150psi through an air horn and people in front of you will think it's Judgement day.:burn:


Steve,

I'm with you. More effective and simpler.

Plus your always ready if you drive into the water.


Jay