95 850GLT Horn going off for no reason

[viper69]

The horn is fed +12 V all the time. In normal operation, when you push the "button" you complete the cirquit by connecting the negative to the horn.
You may have a dirty contact inside the wheel that is causing the intermittent honks, or the wire from the horn to the wheel may have been pinched somewhere allowing for an intermittent short to chassis.

Thanks for the info! It's a really weird issue, esp because no one can duplicate it.

[regent]

I think abscate gave you the best approach already:

You want to troubleshoot two components of the circuit, one at a time:
# 1. the wire between the horn and the wheel switch, and
# 2. the switch itself
Visual inspection is pretty sufficient to pinpoint the offender. I would not worry about wasting time on duplicating the problem.

Here is something that is easy to do: Just disconnect the wire from the horn to the wheel switch, and then run a new wire to connect those two points. You want to leave the rest of the wiring from the fuse to the horn as is, e.g. the horn will be still powered as normal and ready to operate. So, you can drive the car like that for as long as you want, and you may honk when you need to.
Now, if the problem still re-occurs with the new wire in place, then you will know it's a faulty (intermittently closing) wheel switch. And if it doesn't, you will know you've fixed it.

[viper69]

I think abscate gave you the best approach already:

You want to troubleshoot two components of the circuit, one at a time:
# 1. the wire between the horn and the wheel switch, and
# 2. the switch itself
Visual inspection is pretty sufficient to pinpoint the offender. I would not worry about wasting time on duplicating the problem.

Here is something that is easy to do: Just disconnect the wire from the horn to the wheel switch, and then run a new wire to connect those two points. You want to leave the rest of the wiring from the fuse to the horn as is, e.g. the horn will be still powered as normal and ready to operate. So, you can drive the car like that for as long as you want, and you may honk when you need to.
Now, if the problem still re-occurs with the new wire in place, then you will know it's a faulty (intermittently closing) wheel switch. And if it doesn't, you will know you've fixed it.

It was acting up again last night. Similar to my previous post, except rather than tapping the wheel w/my hands at the 7 & 5pm position simultaneously. The horn only went off when tapping on the left side, between the 8pm and 6pm position. It went off the most frequently and loudest at the 7pm position on the steering wheel. I don't know if that is coincidence or if particular wires are located nearest to that section of the steering wheel.

I'll work on it later this week when I get a chance.

I like that idea a lot! I'm not an advocate of just replacing parts for no obvious reason, never done it.

Thanks guys! Excluding 850TurboTurtle in the thanks

[polskamafia mjl]

From your posts it looks like you still haven't looked at the horn contacts in the wheel itself. Your problem isn't the typical failure mode for broken contacts but they are the most common component to break. Take the steering wheel apart and look at the contacts.

[viper69]

From your posts it looks like you still haven't looked at the horn contacts in the wheel itself. Your problem isn't the typical failure mode for broken contacts but they are the most common component to break. Take the steering wheel apart and look at the contacts.

What do you mean by typical failure mode? I never had a horn problem before.

Well, I had brought it into the mechanic and they took apart the wheel a year ago and thought they fixed it, clearly not. It's supposed to go in tomorrow. I want to see physically see what it looks like inside for myself. They are reluctant to do so for liability. I told them I'd sign any wavier, that pictures wouldn't suffice. I haven't spoken to the owner yet, and I'm hoping he'll let me in.

The contacts in the wheel, are these the parts that someone else referred to that might be "cracked" ?

[polskamafia mjl]

The typical failure mode would be the horn sounding all of the time. When the plastic tabs break, the horn circuit is completed and the horn sounds all of the time, not sometimes or just a little bit, the way yours has behaved.

The contacts are exactly what the first couple users have been referring to.