Blaring horn non stop of 2001 mitsubishi montero limited

check horn relay works
get a 12v probe and test the horn switch works when pressed
12v should be supplied to the horn relay coil contact when the horn switch is pushed on.
Also check the fuse.
Check voltage going to horn when pressed
horn might be negatively switched so 12v positive is on one side of horn and relay switches ground negative .
You will find the horn relay under the bonnet in a relay compartment most likely

You need to determine if it's the horn or the alarm. My Montero (not Sport) had 3 horns. All 3 of which go off w/ the Alarm, but only one is connected to the horn on the steering wheel. I could not make mine go off w/o pulling the relay under the hood.

My spring was bad in the steering wheel. I was able to bypass the wire using instructions that I actually found on a Mitsubishi Forum. Link below:

http://mitsubishiforum.com/forum/mitsubishi-montero-montero-sport-14/horn-wouldnt-stop-2003-montero-limited-how-i-fixed-37779/

or

http://www.pajero.guru/how-to-fix-pajero-stuck-horn-problem-step-by-step-guide/

Broken engine mount by the sounds of it.
Would also explain the horn if the + wire is pinched and earthing.

yes you have to remove the steering wheel to gain access ,disconnect battery then remove the air bag after that its relative easy ,air bag either has two 8mm bolts/nuts or a spring clip holding it on

my 97 eclipse did same thing so I had to remove horn relay which is temp.solution but completely immobolizes horn usage.

Is the alarm causing the horn to honk? If so, you need to figure out what is causing the alarm to trigger, which could be any number of things.
Or, the panic module could be failing.
It is least likely to be the horn ring unless the only way you can get the horn to stop is by "beating the horn button on the steering wheel".

If it is, then you can replace the parts for the horn button, but you will need to get an assembly manual for the vehicle. Be sure to disconnect the battery before attempting to remove the airbag module. If it goes off, then you risk injury, and, they are not cheap to replace.

I wonder,, with colder tempratures this time of year, If somehow a connection in the horn pad was shorting out.due to expansion or contraction of a component inside the steering wheel. Try tapping on the top of the air bag on the steering wheel and horn buttons ..this may work ..note this is a guess and I hope this does it the only reason I mentioned it Is because I have seen this two other times...Good luck.

2003 Mitsubishi Montero Limited. 97k miles. Temp gauge is erratic when actual temp is normal. How do I fix this?

The Air Bag module in the steering wheel is no good. The contacts burn and stick.

try spraying some armor all where wheel meets the column covers