electric roof horns

[gordon23]

This is very weird. My roof horns never worked right from the time we bought our used MH this spring.

I took them off and bench tested each and adjusted the coil points screw to get them working.

Hooked up horn "a" by itself and worked fine. Hooked up horn "b" by itself and worked fine. Hooked up both and all I get when I press the horn rim is a clicking sound. Each horn has it's own + & - leads. I tried switching one set thinking there may be a polarity problem but that didn't solve the problem.

Is it possible that the wire leading up to the roof is too small a gauge to carry the current.

Can't say if this wire was original or not but it looks old and brittle.

Can anyone tell me if the horn circuit has a relay between the steering wheel button and the horns. It may be that it's the faulty component.

I've spent hours at the end of a ladder trying to fix this. Maybe I should just have new horns mounted in the engine compartment.

[gordon23]

This is very weird. My roof horns never worked right from the time we bought our used MH this spring.

I took them off and bench tested each and adjusted the coil points screw to get them working.

Hooked up horn "a" by itself and worked fine. Hooked up horn "b" by itself and worked fine. Hooked up both and all I get when I press the horn rim is a clicking sound. Each horn has it's own + & - leads. I tried switching one set thinking there may be a polarity problem but that didn't solve the problem.

Is it possible that the wire leading up to the roof is too small a gauge to carry the current.

Can't say if this wire was original or not but it looks old and brittle.

Can anyone tell me if the horn circuit has a relay between the steering wheel button and the horns. It may be that it's the faulty component.

I've spent hours at the end of a ladder trying to fix this. Maybe I should just have new horns mounted in the engine compartment.

[chasfm11]

Since noone else has replied to you, I'll give you a couple of my thoughts from reading your description.
1. I wonder if your horns are wired in series and they need to be wired in parallel. Your idea about too little voltage may be the result of how they are connected together. To prove it, I'd bench test them together but put the postives and negatives together on the positive and negative power source wires on the bench test. If that works, do the same thing on the roof.
2. There is almost always a relay on horn circuits because the horn buttons (really a switch) cannot handle the current that a horn requires. You can prove that the power source to the horns is not a problem by disconnecting them and carefully hooking up a volt meter to the wires (It will probably be a real pain to isolate the wires from each other and the surrounding material while hooked up to the meter). It is possible to get 12v and not enough current to make the horns sound but I'd leave worrying about this until it was the only thing left. If that is the case, it is probably bad contacts on the relay points.
3. When you made your adjustments to the coil points screw to make the horns blow individually, you may have caused them to draw more current than they were intended to do. I really don't think so but it is possible.

I wish that I had something more concrete to offer to you. I've never seen a situation like you have described.

[Dutch Star Don]

Gordon...Take a separate 12 volt dc line and hook it directly to the horns. That will answer alot of questions as to where the problem is. If they work, you have a power supply issue. If they don't, you have a horn issue. Hope this helps. This is kind of the poor man's test.

[gordon23]

All good advice.

Did a retest on the bench and everyting works. Even with both horns paralleled. On the roof each horn has it's own power supply.(4 leads) Tried them black to black and black to white. No joy.

The voltmeter shows 13.5 when I press the horn button but I have no way of knowing what the current draw is under the coil load of the horns.

With everything hooked up the horn relay can be heard to close and you get a single click noise out of the horns.

I think your suggestion about the points in the relay might be the answer. They may be closing but not properly causing the current to be less than needed.

I have found the relay on the steering column under the dash so I'm going to relace it (if I can get one) and see if that works.

If all else fails I will simply put a set of car horns under the hood.

[gordon23]

All good advice.

Did a retest on the bench and everyting works. Even with both horns paralleled. On the roof each horn has it's own power supply.(4 leads) Tried them black to black and black to white. No joy.

The voltmeter shows 13.5 when I press the horn button but I have no way of knowing what the current draw is under the coil load of the horns.

With everything hooked up the horn relay can be heard to close and you get a single click noise out of the horns.

I think your suggestion about the points in the relay might be the answer. They may be closing but not properly causing the current to be less than needed.

I have found the relay on the steering column under the dash so I'm going to replace it (if I can get one) and see if that works.

If all else fails I will simply put a set of car horns under the hood.

[FloraBama]

After reading this posting I tested my roof horns and they don't work and here I am only 3 days left on my warranty. The underhood horns work just fine so I'm wondering if the roof horns are even wired into the steering wheel.

Would the roof horns have a different switch somewhere?

[RV Wizard]

There very well could be a switch on the dash area to diconnect the air horns. I have seen this on many diesel pushers and it coulad also be on the gas chassis as well.

[gordon23]

you may have an overide switch in the bank of switches on the dashboard. You didn't say if you are diesel or gas engine. In the case of diesel the horn would more likely be air driven than electric.

still can't get mine to work. going for a set of car horns under the hood.

[rayw]

To whom...

I have a seperate switch on the dash for the Hadley's. Off and only the peepers work - On and bye bye eardrums.