Tacoma Horn randomly goes off part 2

Well last night I was woken to my trucks horn blaring at 2 in the morning. I once again had to pull the horn fuse to stop it.So I come here to once again ask for help.

As a recap my truck is a 2001 3.4L Tacoma. It does not have any sort of security system. The horn relay from my understanding is integrated to the ECU. I went ahead and took the airbag out, and sanded the horn contact points down and made sure the contacts weren’t sticking.

It seems like the horn only goes off randomly when I’ve been driving in wet conditions. This weekend I’ll be spending my time looking for a short in the wiring harness which should be “fun”.

I hope I find something thats wrong this weekend because at this point I’m about to tap into the factory wiring harness so I can install a switch, which I really would rather not do, but I’m desperate.

I love my truck and all, but after last night I’m about ready to drive the thing into the Grand Canyon. So any advice would be much appreciated!

 

Have you ever taken the time to figure out why it is on?

then it stops all by itself and works for a few days.

about the only thing is something energizing the horn relay.

Are you driving in Salt Water Fresh water is a very poor conductor and most likely cause it to not work at all.

Maybe you have pissed off someone who likes to blow your horn

The Horn Relay is incorporated with the body ecu.

Most times these thing
gs are caused by Alarms but you don`t have any.

good luck

 

So when this is happening, is the horn just constant ON, or is it "honk, honk, honk, honk"
Constant on would be something grounding the horn circuit.
Honk, Honk, Honk, Honk would be an alarm system.

Prior to 01, the horn was just triggered by the switch grounding the horn relay. In 01 toyota integrated it with the body ECU (which is essentially a smart relay). It doesn't actually have a separate relay, at least from what I can tell on the wiring diagrams.

Either something is going on in the body ECU, or the Green-Red from the horn switch which connects to pin 13 on the body ECU is getting grounded (most likely case).
I have attached the horn circuit for a 03 truck. It really isn't much help other than giving you the wiring colors and pin numbers.

 

Do you have cruise? Does it work?

 

When the horn goes off, it’s a constant noise. Thanks for the wiring diagram! So I’ll go ahead and look at the wiring going to the body ECU.

 

The cruise control does work.

 

It’s only ever exposed to fresh water. So I guess the water wouldn’t be setting it off.