Horn relay question

[shadango]

I spent some time yesterday cleaning up, paintingand tuning the horns on my 72 fish.....they startedoff sounding pretty bad...barely audible.....more of a groan than a horn.

I used a little marvel oil in the tuning screw hole and worked it a bit and lo and behold they are goodas new.....painted them up and reinstalled today.

Well, the horns dont work thru the steering wheel horn contact on the signal switch. 

I took a jumper and jumped the horn roller contact with ground.....a known goodone as well as the steering shaft.....both times just the clicking of the relay....and it sounds like the hrons TRYING but not sounding....

I went back out to the horns and jumped them power straight to the battery and they are fine....

I measured the voltage from the horn roller contact to ground and got a full 12.7 volts (running the stuff from a battery jumper pack)

Is it possible that the relay is bad and not letting enough power through?

Wanted to see what you guys thought before searching for another one.

 

[MEK-Dangerfield]

Yep, it's a bad relay.   

[shadango]

Alright, a bit of a development....

Disconnected ONE horn and the other sounds clear and loud......connect that one back up and disconnect the other, clear and loud.....

So basically, can get both to work fine indvidually, through either connector on the harness....but together they just make a sound like they want to but dont sound at all.

Still a relay?

[Bullitt-]

2-horns take 2X the power to operate

[shadango]

SO the relay just isnt allowing enough power through then?

[Bullitt-]

You stated that you tested the ground using a jumper pack but did not say how you were energizing the horns other than testing each horn by wiring straight to battery. Could you check the voltage to the +connectors when going through the relay circuit? It's possible that poor connections along the way are dropping the voltage or even your battery is not fully charged. The clicking relay tells me that it is working, of course bad contacts in the relay could also limit voltage.

[shadango]

I tested the horns running power straight to the battery, but also tested by using the power leads from the relay itself as it should work.  The horns are mounted to the car, and I made sure I have good ground.....

Through the relay, one horn at a time (either horn, either lead) works great.....together, not.

[Bullitt-]

  It has to be one of two things (or possibly a combination). Either your not getting enough voltage or the horns are requiring too much viltage.
  Replacement relays are hard to come by & a little expensive, a standard 3-prong relay could be wired in place but you would loose the key in ignition warning (a good thing IMO).
  1st check the voltage getting to the horns, if that seems correct exercise the horns to get them working their best, it's also possible the oil is adding to the load so clean them out with contact cleaner.

[shadango]

I measured about 12.? volts at the individual plugs at the horns.

There is a procedure in the manual where you measure amperage across the horns......I guess maybe the oil could be an issue....but again, they sound GREAT seperateley.....

[quapman]

I have the same problem with my 71 Charger. My theory is old, crusty wiring. I've tried relays that work fine in other cars and same problem.

I back up my theory by stating that when I installed a NEW wiring harness on my 70 Chall., the horns got LOUDER!

[shadango]

I did find out that the signal switch on my car had an issue with the contact for the horn ring on the can.....it was broken....I was able to epoxy it back into place, but even then it wasnt making contact....looked to me like the spring is just worn out....

Luckily I picked up a spare signal switch unit on my last parts run and after cleaning the hazard lights switch it is fully functional now......

Gonna try messing with the adjustments on the hrons while on the car.....the manual talks about the amerage of them having to be with a certain range...between the oil and my adjusting them off the car, maybe thats where I went wrong.....I dont have the tool for the adjustment screw though so that will be a real PITA.

[Aracer]

Mine (the relay), was bad from the factory!

[shadango]

Well, I went and ran contact cleaner thru the horn to remove the oil I had put in.....let it dry out well.....

Hooked everything back up and same deal.

I checked each horn alone and they are fine....but have them together and nothing.

I started tweaking the horns and at one point got them working together (I think)....but then they stopped again.....

For now, will run one horn and see if I can locate a used relay that is good....try it.....rather than spend $50 for a new one....wondering if Napa would have one I could use, even if it would delete the key buzzer, just to see?