Intermittent horn

[Shdwdrgn]

Hey folks, '04 Trailblazer and since this Summer my horn has been working intermittently. At first I just assumed one of the switches on the steering wheel had gone bad, but it doesn't seem to make any difference where I press. It will work fine at times, and other times I get nothing at all. At a time when it wasn't working I also checked the front and back fuses (which all look fine), and swapped the relay with the one beside it, but again it made no difference. Then a couple days later it was working normally again.

I'm assuming this isn't a short, or I would have blown a fuse. Perhaps a loose wire somewhere? If so, where would be key points to check? Are there any other common issues that might cause this?

Thanks!

 

[Mounce]

I've heard about the contacts on the wheel being the issue a few times. Where the 'button' behind the air bad is actually pressed.

 

[Mathoran]

Shouldn't be any switches just metal to metal contact that sets off the horn. Maybe take off the airbag and check this thing. The plastic thing with the 2 red wires. If the tabs on it break and its loose the horn wont work. If the horn still works with the remote/alarm its probably this thing.

Or maybe its the actual horns under the hood going bad.

 

[Blckshdw]

I've actually had this exact same problem for a few years now. Ever since I swapped my plain Jane steering wheel for a DIC steering wheel. Haven't been able to figure out what the problem was, because every time I took the airbag out for testing, that's when the horn wants to work 100% of the time.

Maybe take off the airbag and check this thing. The plastic thing with the 2 red wires. If the tabs on it break and its loose the horn wont work. If the horn still works with the remote/alarm its probably this thing.

I remember that connector needing some persuasion to come out, I wonder if I may have snapped off one of those tabs in the process. I'll have to check that out. Thanks for the hint

 

[budwich]

the "thing" in the picture makes contact at the bottom of the "housing"... there is some form of "grease" that causes the contact to not be good. Just needs cleaning.

 

[NJTB]

Same things happening to me. Took it apart twice to find the culprit, found nothing, but when I put it back together it worked.
I've found wacking it with your hand fixes it for a while.

 

[Matt]

Horn don't work, just use your finger.

 

[Blckshdw]

Pulled the horn switch's contact out of the column, and although the wires and spring were a little bent, there was no breakage in the insulation. It was in the column nice and tight, with no play. Straightened them out some, and put them back in place. Didn't think to test the horn beforehand, but naturally, after I put the airbag back in, the horn worked fine. We'll see what happens the next time I need it in traffic...

 

[Shdwdrgn]

So I never had a chance to get back to this, but at least now I know how long since I've posted!

An update on the issue... The horn does not work at all any more, not even an attempt at a beep. I just went through the fuse blocks again today and still no sign of any trouble there. So, without removing the steering wheel (I'm trying to avoid messing with the air bag if I can), are there any suggestions on where else I can check? Places I can check with the multimeter to see if the horn button is working or receiving power?

One thing I forgot to note on the original post: I made one change to the stock system by installing a third horn under the battery from an old Pontiac (gave the sound a little more throat). It occurs to me that newer vehicles may be a bit more fragile to something like this but I would expect to blow a fuse before actually damaging any wires, however I thought I would mention it.

Thanks again for any help.

 

[Blckshdw]

You'll probably have to get the wiring diagram from Moose's signature if you don't have it already, but behind the knee bolster at the base of the steering column, there's a wiring harness connection that goes from the turn signal stalk, and clock spring, to the body of the truck. This is the place where those of us who wanted to do the DIC cluster hack, without the DIC steering wheel, would tap in for the extra button functionality.

 

[Mooseman]

Couple of things to check. the fuse and relay. Check the power there. Try jumping the relay to see if the horn itself is good. Check if you're getting the signal from the switch at the relay.

The link to the manual is in my signature for the schematics.

 

[Shdwdrgn]

Thanks for the replies! For whatever reason, even though I have this thread watched with email notifications, I'm simply not getting them (I do get emails from other subs).

I'll take a poke at things tomorrow and see if I can get any life out of the horn again. I always worry about corrosion around the fuse contacts so I make a point of removing them completely to help clean things up. Hadn't thought of manually jumping the relay, that might help narrow it down to a problem with the steering switch. Re-reading the old comments above, it seems like that might actually be a common problem.

 

[budwich]

The problem that I found is that there is some form of grease (maybe dielectric but I don't think so) which gums up the contact area on the "wiper" which then prevents the circuit from operating correctly. Once cleaned, the horn returns to operation.

 

[Mooseman]

If you do it systematically, you can trace either from front to back or vice-versa. I'd go from the horn for power and ground, if no power, then do the relay jump and check for power at the relay and if the signal is getting to it, if not, then back from there at the column and then into the steering pad. Here's the schematic for reference.