Looking for help with a horn problem...

[ajf3ajf3]

Hi all -I installed an aftermarket horn a few months ago with the instructions found here (thanks!) & it worked great until this weekend...I went ot hit the horn & it didn't honk... lifted the hood & listened while hitting it & I heard a clicking sound. Figured it was the relay I installed - (the original 'hot' horn wire is now the switch for the new relay & I ran a hot wire from the battery to the same new relay to power the horn). The horn does go off when I jumped it straight to the + battery terminal.Anyway, I replaced the relay I recently installed... hit the horn - click again! I take a closer listen (like I should have in the first place!) and find that the clicking is coming out of the fuse box. Guess there's a factory horn relay in there too... pick up a new one at advance ($18!) and snap it in... the new one clicks too! WTH?!?Any ideas what it might be? The horns do beep when I jumper straight to them...Thx!

[joatmon]

clicking is probably the relays activating, which is what you want. You installed a second relay, so that the original horn relay puts voltage on the coil of the second relay. When the second relay closes, it connects the new power wire to the new horn. Did you put a fuse in the new power wire? If so, check the new fuse. (If you didn't fuse it, you probably should have.)If you disconnect the new power wire from the new relay and connect it to the new horn, does the horn sound? If it does, then the power is getting to the new relay, and either the new relay is not activating or there is a problem in the wiring between the new relay and the new horn.Does the new relay click when you hit the horn button? If so, then the control circuit is ok. If not, then even though the original horn relay is activating, it might not be sending power to the new relay, so check the 10A horn fuse in the underhood fuse block. (although the horn relay ower out and dthe 12V to the horn relay coil come from the same fuse, so since the horn relay is clicking, the horn fuse is probably ok)

[ajf3ajf3]

Ok..thx!I thought the clicking was a bad thing... guess it's just normal though.I checked the fuse in the new + wire from the battery - looks ok. Plus I got a multimeter and checked. Putting the black on a bolt and the red on the battery terminal, I get +12. When I move the red to the (B) terminal on the new relay I get + 12. Those seem to be good readings. Strange part is that when I put the red on the (S) switch contact on the new relay that the original horn + goes to I get the same +12 regardless of whether or not the horn is depressed. Well, I get 12.91 when it's not depressed and 12.92 when it is - that seems to be odd.When I jumper the (B)attery and (H)orn contacts on the new relay the horn does go off, so the power from the battery is getting there and the wires to the horns seem to be ok.Things is, this was working for a long while and then stopped without changing anything around - ie would seem to be a component failure more than an install error...

[joatmon]

It sounds like the new relay isn't switching. On the new relay, one end of the coil is connected to the original relay output, which switches between +12V and an open circuit.. The other coil terminal on the new relay should be grounded. Sounds like somehow it's connected to +12V instead. All I can think of is to check the ground on the new relay coil.Can't even guess how it would be that way, having worked in the past. here's a pic showing the orignal setup, and how I think you have it set up for the new horn, is this how you have it?

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[4X4CHICHI]

Mine kept blowing the cheap relays that come with those horns. I finally replaced it with a heavy duty one from Pepboys. It was about $19.00 but it has worked flawlessly so far.

[ajf3ajf3]

Well, that could be an explination... if the new, more expensive one worked ;/One thing I didn't mention... the original relay had a ground plug. This new one doesn't - just a (H)orn, (B)attery, and (S)witch.I'm going to check later to see if the (S)witch wire continues to read 12v when I unplug it from the new relay. That should tell me if it's being sent from the factory relay, or a short in the new relay, right?I'm assuming that that wire should have 0v unless the horn is depressed... is that right?

[joatmon]

My guess is that the new three terminal relay has one side of the relay coil tied to the battery lead, and is looking for a ground to activate. I also think that the output of the stock relay will be an open circuit normally, and 12V when the horn is pressed, and that will never activate the new second relay if it is looking for a ground on the Switch terminal. Sounds like the new second relay is electrically different fromt he first new relay, and that changes the circuit, the two second relays behave differently, and this newest one isn't compatible. It's possible to add stuff to make it work, but the easiest thing would be to get a relay that lets you ground one side of the coil so that you can use the open circuit/+12V output from the stock relay to control it.edit - If the new relay is looking for a ground as a signal to activate, then the cheapest way forward might be to tap directly into the horn signal. When you press the horn, it sends a ground (0V) to the factory horn relay. If you pulled the factory horn relay, you could use you meter to determine which pin on the relay was this ground from the horn switch, and then use a terminal lub in that hole in the relay socket and run a wire off to the new relay's signal terminal.

[ajf3ajf3]

That sounds like it makes sense... could I verify that by removing the original horn wire from the (S)witch terminal on the new relay and jumpering that terming to ground? At that point it should activate if this is the case, right?Also, any recommendations on where to get a 'good' relay? I just picked this up at CarQuest - the only one they had.Thanks again!

[Jahntassa]

Most places should have a standard 'Automotive' 30 Amp relay with either four or five terminals on it. Looks like a small cube with a tab that has a hole in it, and connectors on the bottom. Usually runs like $6 or $7.

[ajf3ajf3]

Thanks guys - that seems to have been it. I replaced the new, groundless relay with one that looks just like the one that came with it (little black cube, 4 prongs, and a plastic mounting tab) and it works fine. The new, new one says 30A on it where the old one didn't, so maybe it'll be better.I thought all horn relays worked the same... good to learn new things