Horn broke (Watch for finger!)

Pat DiPersia

SCCoA Admin
So the horn has slowly been going out on my '94. I really thought it was the switch in the steering wheel because if you pressed it enough and sometimes hard, it would work. And it doesn't get much use. But that's not it. No longer works period.

Started troubleshooting. Switched the relay with the ABS relay next to it (Assuming that's good since I don't know of any ABS issues.) No change. Relay clicks when you hit the horn, and I sent 12V to the relay and verified continuity between the correct pins on the relay.

Checked for 12V at the relay for horn power. Checked out fine. If I jump the pins in the power distribution box, I get a horn. Works perfect.

Even though the relay is clicking, checked for continuity between ground and the relay switch side - good.

So I'm lost. Relay is good. Horns are good. Cleaned the contacts on the relay and tightened up the contacts in the power distribution box (Making the relay really hard to get in and out now) - nothing. While someone held the horn, I plugged the relay in, wiggling it about to make sure it's getting good contact. Nada. Even pulled the power distribution box and watched the wires as I plugged the relay in to make sure one wasn't slipping down (Doesn't look it.)

Any other ideas?
 
The horn is grounded through the bracket, correct? I haven't looked there in a while but if I recall that's how it's grounded. Have you pulled the horn off and made sure there's good clean contact point there or that the bolts holding it in place aren't corroded or dirty? You say it has been going out gradually. Sounds like corrosion may be the issue somewhere along the line.
 
It is grounded through the bracket. I did test this area thoroughly (even removed the horns) but left it out in my post since I get a good horn if I bypass the relay.
 
By bypassing the relay, you're still using the factory wires from the relay to the horn, correct?

If so, problem points to the relay.

Even if the ABS one plugs into the socket, they're not really equal and may not internally be the same. Just a quick search on a parts site shows that the ABS relay and Horn relay are different part numbers, different relays.

The Airtex brand Relay for the ABS in a 94 is listed as P/N 1R1061

The Airtex brand Relay for the horn in a 94 is listed as P/N 1R1727 (3 Terminal) or a 1R2495 (4 Terminal)

I'd try a new horn relay before going further down the rabbit hole on this one. It's the easiest part to replace and less than $20 (depending on which number of terminals you have there). There may be corrosion inside the relay. Even though it is clicking like it should be, the contacts it is closing when you hear the clicks might be dirty or corroded in there. You did mention the sound was getting weaker over time, if the contacts in there are dirty or corroded it could be a gradual degradation of the power amount passing through it.

It sounds loud and clear when you jump the contacts, correct?
 
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Does that car have an aftermarket alarm system?

How old is the multi-wire ignition switch down on the side of the steering column?
 
Yes - when bypassing the relay, I'm just jumping the contact in the power distribution box - so factory wires from the box to the horn. Relays are actually the same - they're both Bosch units (If I recall correctly) and have the same pin-out and part number from Bosch. Only thing I can come up with is maybe the relay can't handle that kind of amperage any more, but it is passing voltage when I push 12v to the relay for testing. Can't imagine they're both bad, but I agree it's the easiest next step to try. Not sure if the relays you're looking at are correct - both are five pin (Though one pin isn't used, center pin between the ground and power for the relay itself if I recall.)

Loud and clear why jumped.

No aftermarket alarm (Don't believe it ever had one.) Ignition switch is factory, though not sure that plays in since the horn is always live.
 
No aftermarket alarm (Don't believe it ever had one.) Ignition switch is factory, though not sure that plays in since the horn is always live.

There is a list of circuits that pass thru that switch that are live regardless. See your EVTM.

Remove the bezel around the column at the dash and check to see if the switch is coming apart. A quick twist of the key should confirm.

If it's original, I'd spend the $17 and treat your SC to a new one regardless.

Good luck.
 
Yeh but would I have 12V at the relay if the ignition switch were an issue?

Depends on how you were measuring it.

Your typical digital meter will barely load down the line; the relay will load it down more.

So you can measure 12V that, due to the poor contacts, drops to 6 or so as soon as the load hits.

RwP
 
Ralph -

Thanks, that makes complete sense. Would a meter that can test batteries under load work for better testing in this instance?

Also, any chance you have a part number or URL for that ignition switch?
 
Pat,
Do you get the proper voltages when using the horn pad on the steering wheel.

I have intermittent issues with the clock spring in my 95's not wanting to work on some days and other days it works. That's small ribbon cable gets brittle after so many years and actually breaks the wires inside the ribbon cable, but on some occasions it will make enough contact to work.

I think it just grounds the horn through the steering column being bolted to the Dash frame if I am not mistaken when you press the horn pad.

Might want to check that too.

Smitty
 
I do; it's a ground line. When I hold the horn, I'm getting continuity between the jumper at the relay and ground. But I agree, I may still pull the wheel apart to see how things look because I really felt like that was a contributing issue.
 
If the relay clicks when you press the horn pad I would suspect corrosion inside the relay. And not enough clean contact to carry the load of the horns.

I had this problem recently on navigation lights on a boat. You wouldn't think that a single 906 style bulb would create that much load that it wouldn't light with dirty contacts at the fuse. fluke meter read 13volts but bulb wouldn't light. Tested the wires running thru the light post with bulb in it on a separate battery and all good. plug post into boat and nada.

I'm going with relay.
 
I do; it's a ground line. When I hold the horn, I'm getting continuity between the jumper at the relay and ground. But I agree, I may still pull the wheel apart to see how things look because I really felt like that was a contributing issue.

Any chance you airbag light flashes on really cold days?

Mine does that and I get a 34 code which is the drivers side airbag. I think the wiring shrinks just slightly losing connectivity. When it is warm outside or after running for a while to warm the interior it never blinks. Go figure..

If you replaced the relay in question with a known good relay, it can't be the really can it?
 
We have a winner! Relay it is. Popped a new one in today and we have a horn. Replaced all four relays and I now have fog lights again, too. There are two identical relays in there, one of which is for the fogs - swapped the relay with the one next to it and still no fogs, so probably not a bad idea to just swap all four.

Thanks for playing along folks! Really appreciate the help.
 
We have a winner! Relay it is. Popped a new one in today and we have a horn. Replaced all four relays and I now have fog lights again, too. There are two identical relays in there, one of which is for the fogs - swapped the relay with the one next to it and still no fogs, so probably not a bad idea to just swap all four.

Thanks for playing along folks! Really appreciate the help.

It's a good feeling when things just work right. No doubt fixing the horn made your car run smoother and drive way better (Feels like it anyways..) Glad you got it going.
 
Well, might not drive better, but I know my mechanic gave me a hard time last year at inspection time about it barely working!
 
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