Horn on constantly...help (4 Viewers)

[tac1983]

Any luck forger? Im having almost the exact same issue.

PO didn't have the best memory of the vehicle history, but said the alarm went off once and drained the battery over a long weekend/fried the horns. Replaced the horns. But had to pull the fuse after the horn would stay on.

I replaced the horn relay and no luck. When the fuse is in the fog light turns on, regardless if they are switched on or not. With the fuse back in, the horn is off and as soon as I press It, it stays on until I pull the fuse or disconnect the horn grounds.

I have .24-.26 across legs 1-2 and 12v+ across legs 1-3, which isn't correct per previous posts.

I saw a raw wire dangling under the steering column and thought it was the issue. I pulled the steering column cover and lower dash panel, and it turns out it was from a previous PIAA switch and not connected to the horn in any way. I haven't pulled the steering wheel yet to inspect the switch there as its getting dark outside.

Did anything work?

 

[TheForger]

Any luck forger? Im having almost the exact same issue.

PO didn't have the best memory of the vehicle history, but said the alarm went off once and drained the battery over a long weekend/fried the horns. Replaced the horns. But had to pull the fuse after the horn would stay on.

I replaced the horn relay and no luck. When the fuse is in the fog light turns on, regardless if they are switched on or not. With the fuse back in, the horn is off and as soon as I press It, it stays on until I pull the fuse or disconnect the horn grounds.

I have .24-.26 across legs 1-2 and 12v+ across legs 1-3, which isn't correct per previous posts.

I saw a raw wire dangling under the steering column and thought it was the issue. I pulled the steering column cover and lower dash panel, and it turns out it was from a previous PIAA switch and not connected to the horn in any way. I haven't pulled the steering wheel yet to inspect the switch there as its getting dark outside.

Did anything work?

Unfortunately I've had no luck or progress with this issue. I've been driving around without a functional horn which is certainly less than ideal. I don't have the fog light symptom, as a matter of fact I don't even have factory fog lights I have Rigid pods that are wired to an auxiliary switch. I did try replacing the horn relay with a new one since it's relatively cheap but no luck. I do share the same issue where if the relay is in then the horn will remain off until it is pressed on the steering wheel, then it will not shut off until the relay is removed. I'm open to all possible solutions

 

[ramangain]

If you were to connect a wire directly from the horn signal "output" in the steering column to the relay, does the horn turn off when you stop pressing the horn? You'd need three wires to test it this way so the other two legs of the relays go through the fuse box.

I'm curious if there is an intermediate connection causing the issue, or potentially something inside the fuse box, on the underside, that is causing the issue.

 

[tac1983]

Unfortunately I've had no luck or progress with this issue. I've been driving around without a functional horn which is certainly less than ideal. I don't have the fog light symptom, as a matter of fact I don't even have factory fog lights I have Rigid pods that are wired to an auxiliary switch. I did try replacing the horn relay with a new one since it's relatively cheap but no luck. I do share the same issue where if the relay is in then the horn will remain off until it is pressed on the steering wheel, then it will not shut off until the relay is removed. I'm open to all possible solutions

Did you previously do the FSM recommended test with the continuity on the terminal and ground point behind the steering wheel?

Im going to pull the wheel this week and have a look at the switch and the ground contact points.

I had an unrelated short in the wire harness connecting the drivers window switches. I was able to fix that but the sheer amount of wires/connectors etc under the dash is daunting. I had a little surface rust near the kick panel that I didn't expect to see, but living in San Diego we rarely get any rain and definitely haven't had any recently to cause the problem. If its an issue somewhere in the wire harness, Im probably going to give up. My dad suggested direct wiring in an auxiliary push button switch to the horn that would mount somewhere on the dash or steering column to at least give me a functioning horn - I hope it doesn't come to that, but a horn is definitely necessary in Southern California.

 

[TheForger]

If you were to connect a wire directly from the horn signal "output" in the steering column to the relay, does the horn turn off when you stop pressing the horn? You'd need three wires to test it this way so the other two legs of the relays go through the fuse box.

I'm curious if there is an intermediate connection causing the issue, or potentially something inside the fuse box, on the underside, that is causing the issue.

Hmm not a bad idea! I'm out of town until Wed but I might try that next weekend. So you're saying run a wire from two legs of the relay back to the corresponding locations in the fuse box under the hood, and another going from the last leg of the relay to the horn output wire under the steering column? Trying to visualize it the best I can without having the truck in front of me. Here's a screenshot of the EWD

Did you previously do the FSM recommended test with the continuity on the terminal and ground point behind the steering wheel?

Im going to pull the wheel this week and have a look at the switch and the ground contact points.

I had an unrelated short in the wire harness connecting the drivers window switches. I was able to fix that but the sheer amount of wires/connectors etc under the dash is daunting. I had a little surface rust near the kick panel that I didn't expect to see, but living in San Diego we rarely get any rain and definitely haven't had any recently to cause the problem. If its an issue somewhere in the wire harness, Im probably going to give up. My dad suggested direct wiring in an auxiliary push button switch to the horn that would mount somewhere on the dash or steering column to at least give me a functioning horn - I hope it doesn't come to that, but a horn is definitely necessary in Southern California.

Have not done continuity test, will do that next time I have the airbag out though. Keep us updated! If I have time I'll tear into it this weekend too

 

[ramangain]

Hmm not a bad idea! I'm out of town until Wed but I might try that next weekend. So you're saying run a wire from two legs of the relay back to the corresponding locations in the fuse box under the hood, and another going from the last leg of the relay to the horn output wire under the steering column? Trying to visualize it the best I can without having the truck in front of me. Here's a screenshot of the EWD

View attachment 2524051
Have not done continuity test, will do that next time I have the airbag out though. Keep us updated! If I have time I'll tear into it this weekend too

Close. Best if you can directly tap the output from the device that closes (I assume some sort of contact switch and goes high 12V) when the horn is pressed. Bypass God knows what between that device and the relay.

 

[Placemotorsports]

Mine was odd, when I took out the fog light relay, I could use the horn and it wouldn't blow all the time

 

[tac1983]

Mine was odd, when I took out the fog light relay, I could use the horn and it wouldn't blow all the time

Those electrical demons sure are sneaky. Thats too easy to not at least try.

Will report back with any findings but doesn't look like Im going to get to any of it today.

 

[diego355]

Guaranteed is water getting into the cab.
It runs down the A-pillar, goes into the junction box.
I just dealt with this issue, unfortunately the windshield has to come out to fix it properly.

 

[tac1983]

So I had a few hours today. I pulled the airbag and all the wires looked good around the column.

I did notice a few interesting, probably not supposed to be that way things when I was checking stuff.

There is rust on a couple of the brackets on the LH drivers side kick area. We haven't had any rain of note leading into the start of the problem, but possibly some prior damage was done.

Even when I pulled the fr. fog light fuse from the kick panel fuse box, the fog light still goes on, when I put the horn fuse back in, but it turned off when I turned the foglight "on"

This is leading me to suspect that at some junction down in the kick panel area there is some sort of rust/damage/short causing the horn to stay on and the fog light to get power, even when its not supposed to. The elusive "P2" relay from previous threads? The fog light relay that placemotorsports said?

How do you access those relays? They're in the driver side kick panel area, near that secondary fuse box correct?

 

[jamief]

I'm curious how the fog light and horn would be related? I don't have fog lights on mine (previous owner deleted with bumper replacement) so I can't test them to know if it's related to my horn issue. My horn issue corrected itself after a few days. I just pulled the fuse and ignored it. Today I went to check for moisture and on seeing none put the fuse back in and it works correctly now. Maybe it dried up or maybe I've got something else going on.

 

[axe127]

I’ve got the same issue going on, too. Horns stuck on constantly (one fried) after a heavy rainstorm this summer, so I pulled the relay and have just been starting to dig back into it. The truck isn’t my daily, but not having a horn makes you realize how necessary it is.

Similar to tac1983, I’ve only got 12V across legs 1 & 3, not legs 1 & 2. I’ve also got some rusted brackets in the driver’s kick panel area, and I’ve identified a water leak at the A-pillar that runs down into there. I had the same thought, that maybe the rust has caused a short. I poked around in there this weekend and didn’t see any obvious grounds that were affected. Next step may be to pull the fuse boxes and do some experimenting with the fog light relay. I believe it’s R7 in this diagram: Fuse Box Diagram Toyota Land Cruiser (100/J100; 1998-2007) - https://www.google.com/amp/s/fuse-box.info/toyota/toyota-land-cruiser-100-j100-1998-2007-fuses-and-relay

 

[jakesiar]

I’ve got the same issue going on, too. Horns stuck on constantly (one fried) after a heavy rainstorm this summer, so I pulled the relay and have just been starting to dig back into it. The truck isn’t my daily, but not having a horn makes you realize how necessary it is.

Similar to tac1983, I’ve only got 12V across legs 1 & 3, not legs 1 & 2. I’ve also got some rusted brackets in the driver’s kick panel area, and I’ve identified a water leak at the A-pillar that runs down into there. I had the same thought, that maybe the rust has caused a short. I poked around in there this weekend and didn’t see any obvious grounds that were affected. Next step may be to pull the fuse boxes and do some experimenting with the fog light relay. I believe it’s R7 in this diagram: Fuse Box Diagram Toyota Land Cruiser (100/J100; 1998-2007) - https://www.google.com/amp/s/fuse-box.info/toyota/toyota-land-cruiser-100-j100-1998-2007-fuses-and-relay

Check your sun roof drains, chances are they are clogged and causing water to leak on the driver side floor. I had this issue, cleaned drains and kept the fuse/relay pulled until all was dry in the floor area.

 

[TheForger]

Thought I'd give it another test yesterday evening and I'm still experiencing the same issue, except I also have the fog light symptom. I mentioned earlier that I no longer have fogs and that I wasn't experiencing that issue, but I do have an LED strip inside of my grille and front bumper that is hooked into the circuit. After replacing the horn relay thinking it would magically start working normally again, everything seemed to work just fine. Drove around and the horn responded as it should. I then parked and locked my doors and started walking away. Like I said this was in the evening so as I was walking away I realized that LED strip was still illuminating the ground underneath the front of my truck so I went back, unlocked, flipped the fog light switch to OFF (it should turn off after locking the truck anyway not remain on to drain my battery), and the horn immediately started blaring. Not sure what the issue is but we haven't had any substantial rainfall in a while so everything is dry, I'm thinking corrosion caused by previous water ingress has built up to the point it's causing a constant short. Between starting a new job and closing on a house at the end of this month I've had to put this issue on the back burner for now, but hopefully a solution will come up soon. I hate not having a horn

 

[axe127]

Check your sun roof drains, chances are they are clogged and causing water to leak on the driver side floor. I had this issue, cleaned drains and kept the fuse/relay pulled until all was dry in the floor area.

Thanks for the suggestion. Drains are clear. There’s water coming in at the top corner of the windshield due to a poorly done windshield replacement under previous ownership. I pulled the A-pillar trim and can see the water running in there and down to the kick panel area.

Unfortunately that’s also caused some rust around the windshield frame, so I’ll need to address that to really prevent the issue from coming back after it’s fixed.

 

[jamief]

I've got rust around my windshield frame. The only way I can see fixing it is to pull the windshield do the repair, repaint that area and then get the windshield reinstalled. Is there any other way?

 

[axe127]

Thought I'd give it another test yesterday evening and I'm still experiencing the same issue, except I also have the fog light symptom. I mentioned earlier that I no longer have fogs and that I wasn't experiencing that issue, but I do have an LED strip inside of my grille and front bumper that is hooked into the circuit. After replacing the horn relay thinking it would magically start working normally again, everything seemed to work just fine. Drove around and the horn responded as it should. I then parked and locked my doors and started walking away. Like I said this was in the evening so as I was walking away I realized that LED strip was still illuminating the ground underneath the front of my truck so I went back, unlocked, flipped the fog light switch to OFF (it should turn off after locking the truck anyway not remain on to drain my battery), and the horn immediately started blaring. Not sure what the issue is but we haven't had any substantial rainfall in a while so everything is dry, I'm thinking corrosion caused by previous water ingress has built up to the point it's causing a constant short. Between starting a new job and closing on a house at the end of this month I've had to put this issue on the back burner for now, but hopefully a solution will come up soon. I hate not having a horn

Sounds like you, tac1983, and I all have the same exact issue.

I’ve checked periodically since the issue started this summer and I’ve had 12V at the horns the whole time, even after long periods of no moisture. So I’m thinking it must be corrosion causing a short.

It would be great to figure out where the fog light and horn circuits come together, since they are both affected. I’ll try to dig through some diagrams and see if anything stands out.

 

[axe127]

I've got rust around my windshield frame. The only way I can see fixing it is to pull the windshield do the repair, repaint that area and then get the windshield reinstalled. Is there any other way?

The rust is likely under the windshield too, so that’s the only way. I got an $1850 estimate yesterday to get it done. Steep, but probably worth it since the rust will just get worse and the leak may cause more electrical issues down the line.

 

[lelandEOD]

I had this same issue and I fixed it today so I thought I'd update the thread in the hopes it helps someone else.

I recently came into possession of a 2002 LX470. I noticed the horn was in-op the other day so I began to investigate. The 10A HORN fuse was suspiciously absent and when I tried to put a fuse in the relay box it immediately started blaring. I reviewed the wiring diagram and checked voltages at the relay. I was suspicious of the horn switch at the airbag or possibly the wiring between the column and the relay. When I pulled the airbag the issue became clear.

The airbag and it's frame are supported by 4 allen cap screws and, since the airbag frame doubles as the horn contact, it is supposed to be isolated from the steering wheel by four white nylon grommets. These nylon grommets support the horn springs and keep the horn from constantly completing the horn circuit ground. One of these four nylon grommets had lost the little nylon tabs which insulate the horn button (air bag frame) from the steering wheel.... causing the horn to sound incessantly. The solution was as simple as adding a rubber fender washer between the airbag frame and steering wheel. Now the horn works as it should.


Cheers!
Lee

 

[Dryhop]

I had the same issue this morning. At 6AM the horn started blowing... and I ultimately disconnected the battery GND to shut it off.

In my case, I'm suspecting the relay is partly at fault. I just reproduced the issue, and a single tap on the relay with a wrench caused the horn to stop blowing. I'll start by replacing the relay... but that doesn't explain why the horn switched on at 6am! I suspect I'll be further debugging after getting a new relay...