Chrysler Repair: 2004 Sebring; Horn sounds spontaneously, fuse box, clockspring

Question
I just got home (work out of state) and my wife tells me that the horn starts going off by itself.  It will happen while driving and while sitting in the driveway at night.  It is a solid horn blast for about 20 seconds or so and then stops by itself.  Other than hitting a huge pothole and replacing a rim/tire, the car has not been in any accidents.  Is there something to replace or is an exorcist in order?

Answer
Hi Jim,
The horn circuit is provided with battery power at all times so nothing supernatural is going on here. There are two switches involved in actuating the horn: the horn relay which when closed will send current to the horn and the "clockspring" in the steering column that provides the connection to the steering wheel horn button, which when grounded activates the relay's switch. It is more likely that the clockspring has developed a direct short to ground due to a broken internal wire. There is one further wrinkle: the actuation of the relay is intermediated by the body controller which also needs to activate the horn as part of the anti-theft alarm system but if that where the cause it would probably also flash the park, tail, and headlights while the horn was falsely sounding. The most likely cause is the clockspring which you could assess by noticing if you can cause the horn to sound be repeated turning of the steering wheel to prompt the false grounding. Or when it blasts on its own accord turn the wheel slightly to see if that cuts off the horn.
If that doesn't reveal a fault you could try switching the horn relay with a similar relay such as the adjacent headlamp delay relay in the under dash fuse box (they are side by side) which if the horn stopped its issue and instead the headlamps came on for no good reason would tell you that the horn relay is spontaneously closing its switch and therefor needs to be replaced).
If neither approach is revelatory, then the body computer would be suspect. But verification would be in order due to the cost.
Roland
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