: Faulty steering wheel horn switch?



AAIIIC
05-08-13, 01:14 PM
Recently I've had an issue with my horn being intermittent. Of course, you tend to discover that the horn doesn't work at a time when you really want it to work, so this started with a heart-stopping moment in traffic about 10 days ago.

When I was working on my oil cooler install I had removed the horns to give myself room to work, but once I got the car home after nearly being hit I verified that I had plugged the harness back in (that was my initial thought, that I had left them unplugged). I also checked the fuse - good - then testing the horn. BEEP! Huh, that's strange. Maybe the harness plug wasn't quite seated all the way?

A few days later the horn worked just fine, so I thought I had fixed whatever the problem had been. But yesterday I once again had someone try to merge into my front fender, and once again the ol' horn didn't work. :mad: Based on the intermittent nature of the issue, I'm wondering if the switch in the steering wheel is going bad.

I have the full FSM at home, but haven't cracked it open yet to take a look. I've never had my steering wheel off or removed the center air bag module - anyone know if the horn switch is part of that (and thus not serviceable separately)?

darkman
05-08-13, 02:12 PM
HORNS SYSTEM DESCRIPTION AND OPERATION

SYSTEM DESCRIPTION
The horn system consists of the following components:

HORN fuse
RADIO fuse
Horn relay (http://www.alldatadiy.com/alldatadiy/DIY~V36757625~C40138~R0~OD~N/0/108596970/110536423/110536424/110536428/34853741/34867926/34872174)
Inflatable restraint steering wheel coil
Horn switch (http://www.alldatadiy.com/alldatadiy/DIY~V36757625~C40138~R0~OD~N/0/108596970/110536423/110536424/110536428/34853741/34867926/34872175)
Horns
Body control module (BCM)
Steering wheel radio control switch
SYSTEM OPERATION
The vehicle horn system is activated under the following conditions:

The horn switch (http://www.alldatadiy.com/alldatadiy/DIY~V36757625~C40138~R0~OD~N/0/108596970/110536423/110536424/110536428/34853741/34867926/34872175) is depressed.
The body control module (BCM) commands the horns on. The BCM commands the horns on under any of the following conditions:
When the content theft deterrent system detects a vehicle intrusion. For further information refer to Content Theft Deterrent (CTD) Description and Operation in Theft Deterrent.
When the keyless entry system is used to lock the vehicle, a horn chirp may sound to notify the driver that the vehicle has been locked. The notification feature may be enabled or disabled through personalization. For further information refer to Keyless Entry System Description and Operation in Keyless Entry.
When the OnStar(R) system is used to sound the horns if equipped. For further information, refer to OnStar Description and Operation in Cellular Communications.
CIRCUIT OPERATION
Battery positive voltage is applied at all times to the horn relay (http://www.alldatadiy.com/alldatadiy/DIY~V36757625~C40138~R0~OD~N/0/108596970/110536423/110536424/110536428/34853741/34867926/34872174) coil and the horn relay switch. Pressing the horn switch (http://www.alldatadiy.com/alldatadiy/DIY~V36757625~C40138~R0~OD~N/0/108596970/110536423/110536424/110536428/34853741/34867926/34872175) applies ground to the horn relay control circuit. The BCM may also apply ground to the horn relay control circuit as described above. When the horn relay control circuit is grounded, the horn relay is energized and battery positive voltage is applied to the horns through the horn control circuit. The horns sound as long as ground is applied to the horn relay control circuit.




Other than a loose connection/ground, the horn rely looks likes the best candidate for intermittent malfunction.

AAIIIC
05-08-13, 03:04 PM
Yeah, I thought the same thing as I read through that list of components. I'm surprised there's a separate relay for something as simple / low draw as a horn, but I guess since it's triggered a couple of different ways the relay makes sense.

I have the horn turned off for alarm activation/deactivation, but I can turn that function back on and use that to do some troubleshooting of the horn switch vs. horn relay.

barrok69
05-08-13, 04:21 PM
Yeah, I thought the same thing as I read through that list of components. I'm surprised there's a separate relay for something as simple / low draw as a horn, but I guess since it's triggered a couple of different ways the relay makes sense.

I have the horn turned off for alarm activation/deactivation, but I can turn that function back on and use that to do some troubleshooting of the horn switch vs. horn relay.

Have you had your steering wheel off lately? There is a small blade style connector behind the airbag in the center of the steering wheel that powers the horn. Get a small screw driver and pop the airbag off (battery off of course) and check the blade connection.

AAIIIC
05-08-13, 07:12 PM
OK, still acting funky, but right now it's working. Came home, went out and tested the horn. Nothing. Turned on accessory power, set the remote keyless to honk the horn when I locked the car. Got out, locked the car. No horn. Aha, it must be the relay! But then I stood next to the car and reached in to honk the horn - with the hood up, I could hear a click each time I hit the horn on the steering wheel. Presumably, that was the relay, so the relay was actually working.

So, off came the radiator shroud so I could reach down behind the grille. This time, rather than just visually verifying the harness was plugged into the horns as I did a couple days ago, I unplugged it, then plugged it back in and made sure it was fully seated. Horn works! Hooray! We'll see how long that lasts. :)

darkman
05-08-13, 07:20 PM
We'll see how long that lasts.

Until you fix something else.............