Alright, so first off, as the username states, i'm by no means a mechanic or know a lot of technical terms. I like to think i'm not a complete horses @s$ however, but this one has me completely 100% mind boggled. I've done the quick google search and keep coming up empty. the best way I can describe it to you is...

Today I went to the gas station, put some fuel in, and went to the grocery store, everything was as normal. after I left the grocery store, I went home and got out and again, as normal, used the key fob to lock the doors on my way to the house.
to my shock and amazement, the horn sounded, but constantly and wouldn't stop! I tried to keep calm but let's face it, when you live in a busy city, I was mortified. I kept repeatedly hitting my unlock, lock, anything I could think of then just stuck with pounding the unlock button on my key fob and kind of rocking the car (I don't know why, thought maybe it was a brake issue or something, or maybe because I know the horn is located in the front, I dunno, I was panicked and mortified!) FINALLY the horn ceased. I looked down to my key and noticed that I was using my spare set, so me being the idiot that I am, decided I would try again, but this time with the key fob I always use. as luck would have it, the horn sounds again, this time worse, I can't get it to sto no matter how much I pound the button or rock the car. I get in, turn on the ignition, thought maybe moving it would help....NOPE! didn't matter if I was in park, reverse, drive or neutral, that sucker wouldn't stop (and yes I drove the car enough to move it out of it's position) so I put it in park and notice that my e-brake light is on, but I didn't put the e-brake on, I haven't for months. I thought my battery had died and then remembered I was still pounding on the unlock. so I get in to start the car to see if the battery did in fact die or if the unlock button finally worked. the car started, again - e-brake light on, I let it sit in idle for a bit and finally the light went out. I was too terrified to use the key fob again. so I locked the doors inside and got out. (those still work ok)

the only thing I can tell you that was different than any other day is this:
we've had some pretty hot days the last couple of weeks, and today it rained.

I hope that someone has some sort of idea of what this could be! I've read a couple of other posts about headlights being affected, but i'm not having that issue, some say also it's only in drive or reverse, again, not that issue. as for the sound of the horn, it's a constant horn, as if I was inside, pushing on the horn without release.

I am truly speechless, and have no idea where to start, and because murphy's law appears to be my best friend these days, I have a job interview tomorrow.

please tell me i'll at least make it there without any troubles. i'm about ready for a mental breakdown, and if my CAR breaks down, that should do it.

please help, and not with technical terms :'( :'(

2005 Mazda3 2.0 - Automatic

 

So a couple of questions and a few trouble shooting ideas

Is the horn sounding when you click lock only once to lock all doors, or are you clicking lock twice to get the horn confirmation?

Will the horn stick on if you just push the horn button on the steering wheel?

If it's sounding when you click once then that's by far super weird. If it's sounding when you click twice then the horn it being triggered as appropriate, however the circuit is staying closed instead of just chirping once. That leans me towards an issue with the horn circuit itself vs. the remote. If the horn continues to sound when you just hit the horn button on the wheel then it's definitely not related to the remote.

So first things to test.
1) Locate the horn relay. This should be located in the fuse/relay box in the engine bay near the battery. Once you have found this you can start testing things out..... because if the horn gets stuck on you can just pull the relay and it will turn off.

2) find another circuit which uses the same relay but isn't vital to what you're testing.... there should be several other relays in the box you can pull.

3) test with locking via the remote (or via the horn button if that gets it stuck too)

4) if it sticks on pull the relay

5) put the relay back in and see if it's still blowing the horn, if it is swap it with another one and see if it turns off.

6) if it did turn off try the whole process again with the second relay.

7) If that fixes it you probably just have a sticky relay, replace it and you're good.

8) if not then try replacing the horn itself (not a bad idea anyway since the stock horn is sort of terrible) since it may be stuck on.

My bet is the relay.