troubleshooting a horn circuit

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steveh

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Several posts out there on horn circuits...using them and an old service manual I determined the following:

What (I think) I know

1. Both horns are good--jumper wire from battery to each horn

2. Wiring is good--test light lit up when I attached to B terminal connector.

3. Relay is good--horn sounded with jumper wire on the H and B terminals

4. Ground is good--test light lit up when I touched it to the B terminal on the relay

So I think the issue is in the steering wheel contacts. Before I dig into that, I wanted to check with the group to see if i am overlooking the obvious here. Would greatly appreciate you thoughts before I start tearing the steering wheel apart.

Steve
 
It doesn't SOUND (no pun intended) that you "checked" the relay.

The relay OPERATES when you GROUND the horn button terminal, not jumper it to another terminal,

One terminal is hot goes to battery

One terminal goes to horns

Third goes to button. So to check the relay you ground that terminal.

The button wire goes directly to the button. I don't know what year model you have, so is the relay out in the bay, or inside the car?

So the button wire goes through the bulhead connector if out in the bay, and that terminal may be corroded. It then goes up through the connector at the column and you can check it there.

Most likely suspect is the button itself.

You need to post the year/ make / model of your car

You can download some factory service manuals right here:

http://www.forabodiesonly.com/mopar/showthread.php?t=132309&highlight=manual,+download

You can download "alternative" diagrams from "My Mopar:"

http://www.mymopar.com/index.php

Over at the left, hit "tools/ reference"

http://www.mymopar.com/index.php?pid=31

then "wiring and electrical"

http://www.mymopar.com/index.php?pid=18

and finally "wiring diagrams"

http://www.mymopar.com/index.php?pid=24
 
67Dart 273,

thanks for the response. it is a 67 Barracuda...so the relay was in the bay mounted near the horns.

Looking back at the shop model, I may have missed a key step.

Manual says..place jumber between B and H terminals, If the horns operate the horn relay is faulty." Horns didn't go off, but I didn't press the horn ring at the same time. Not sure if that would make a difference.

Went ahead and pulled the horn contact out of the wheel. Assembly is held together with three rivets...but looks like the only metal to metal contact is at the edges of the two disks...If that is correct, then some light sandpaper around the edges should clean that up.

Two other possible issues, black ground wire in the wheel is pretty smashed and one of the three rubber detents on the horn switch is badly bent will post some pics once I find the flash card.

Thanks again...this site and the folks on it are absolutely great. Only wish I could add value too...but my skill level is slim to none so I'm often reluctant to chime in.
 
So here are two pics (horn switch and wire) Judging from the flat as a pancake spots on the wire I suspect I am getting no power to the contact assembly.

Stupid question but can I use the test light to check the continutity of this wire?

thx again
 
doh...this time with pics

in addition to horn troubles, i cant figure out how to attach the pictures.
 
The horn button wire should be hot by way of the relay coil. That is, the relay coil is hooked to the battery terminal of the relay, goes through the coil, and clear up to the horn button. You should be able to ground that wire either at the relay or at the button connection and get the horn to sound.

Two popular button problems is the wiping contact brush/ ring in the wheel worn/ dirty, and the horn button contacts dirty / corroded.

Here's a shot of the relay in the engine bay:

The top terminal, H2-16 dark green, feeds to the horns

The middle terminal, H1-16 violet is battery coming in

The bottom terminal, H3, no18 black, goes to "W" of the bulkhead connector and is the horn button wire

24qn8s5.jpg


In the interior, following from "W" in the bulkhead connector, H3 is shown as black with tracer, goes over to no4 in the the column connector and up to the horn button switch

4iiira.jpg
 
I pulled the steering wheel today and cleaned the contacts (the copper ring under the wheel as well as the assembly that sits under the horn ring). Put it back together and still no horn. Would appreciate your thoughts on where the problem might be.


1. One of the buttons on the contact assembly appears broken see attached pic. Maybe thats part of the problem...but other two buttons should work.
View attachment horn switch.JPG



2. is there a way to use a test light to isolate the problem at the steering wheel? The lead coming from the contact ring and plugs into the switch should be hot right? Notice how mine is flat as a pancake in 2-3 spots maybe the wire is broke inside. View attachment Contact lead.JPG


3. Couldn't find the horn ground wire that runs from the column to the dash? thats probably part of the problem too


Lastly, Somebody has pulled the wheel recently, retaining nut was only hand tight and wheel slipped right off with only a slight tug.
 
put that smashed wire at the steering wheel against the nut--- horns should be blaring--- if they don't --check your column wiring & connection point ,Lawrence
 
VDART said:
put that smashed wire at the steering wheel against the nut--- horns should be blaring--- if they don't --check your column wiring & connection point ,Lawrence
Click to expand...

Exactly.png


You should be able to narrow this down in about two minutes

Ground the wire hooked to the button to a good ground IF the horn does not sound------

go out to the engine bay after referring to the diagram showing the horn relay. Ground the black wire as shown on the bottom of the relay. If the horn does not sound, its "right there." If it does, it's the horn button wire from the relay to the button.

If the horn DOES sound up at the button when you ground that wire, it is either the switch itself, or the BRUSH AND SLIP RING under the wheel.
 
steveh said:
Yep, it was the relay...Many thx
Click to expand...

Tell you what, if you read this before you buy a new one

I have a brand new NAPA one that was on the car about two weeks. I just rewired using a Craigslist Painless harness, and the relay is now on the fuse panel.

If you want that relay, you can have it for shipping.
 
FWIW, my normal method of testing the ends of a circuit and working inwards, I have found, is not efficient way to troubleshoot electrical problems on our Scamp.

My problem was that I didn't realize (should have been obvious) that the horn button wire is only hot when the relay is getting power, and is working properly. In my situation, I had corrosion on the relay connector, and in the relay (had to replace the relay) that caused a voltage drop. I also had bad column grounds to fix. Lastly, the fuse looked ok - but there was corrosion on the metal ends of the fuse panel terminals as well.

I have been using electrical terminal grease now when I am connecting everything to together. Makes a big difference.

One other point. The horn roller connector is/was loose on my switch, which was causing intermittent connectivity. (I realized I was getting voltage on the spring below the roller, but not the roller itself unless the roller was pushed to one side. In order to get inspected, I used a few copper wire strands between the roller and the shaft to tighten up the roller connection. You can see the gap on each side of the roller in this pic.
 

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