Phantom Horn Blower... Gen 2.5

[nwoods]

Yesterday while starting the 1998 Monty, the horn started blowing, not in any sort of sequence, such as an alarm, just... random horn noises. It only did so with the ignition key inserted and turned to the ACC or Start/Run position. So with the car running, the horn was occasionally sounding off every few seconds or so. I double checked, it was not the cheesy dealer installed security alarm horn, but the main horns at the front radiator.

So I pulled the 10amp fuse for the horn and drove to work, but I am perplexed as to what might be happening. Any suggestions?

 

[tlr]

Could be a short in the wires to the horn?

 

[Jay Ayala]

I had something similar happen. I found that the padding sponge material under the steering wheel had written all the way down causing the metal flap on the steering wheel to make contact with the horn conductor. I had to clean and replace the sponge material.

 

[nwoods]

Jay, is this within the steering column itself? I can easily pull off the plastic trims that clad the steering column. What did you use for replacement sponge material? Where did you source it?

My other theory is something called a clock spring. I don't know what it is, but it popped up a few times in my google searches. My steering wheel grumbles as I turn, sort of sounds like plastic gears bouncing around out of alignment. I don't know how else to describe it. Was wondering if they are related.

How do you replace a clock spring? What does it do?
EDIT: Here is a great video about the clockspring, starting at about the 1:25 mark: https://www.youtube.com/watch?v=oPPK3ylztcs

 

[nwoods]

The clockspring is item 7 in this diagram (just behind the airbag)

 

[jlocster]

Nathan, I'm willing to bet it's the membrane switch that is actually part of the airbag module. Turns out this is a very common failure. For the record, I'm in the same boat...my horn has been stuck "on" since I bought the vehicle.

Assuming it is the membrane switch, here are your options:

Plan A
The switch itself can be fixed, but its dangerous to do so because to access it you have to mess with the airbag itself.

Fixing the switch yourself:

Plan B
Buy a new airbag module from Mitsubishi.

Plan C
Tap the horn circuit and wire a separate horn button somewhere on the dash.

EDIT: Just reread your post about the grinding sound when you turn your wheel. Yes, it could be a contact failure in the clock-spring. That said, I haven't come across many clock-spring failure posts, where I have come across many posts regarding the membrane switch failure.

Good luck!

 

[Sabre]

Not complicated, but be aware that working with the airbag module calls for EXTREME caution. It is pretty much a hand grenade just waiting for a stray low-voltage current to explode.