2007 Toyota Yaris horn not working

[desidude]

Hi friends,

I hope everyone is doing well. I have a 2007 Toyota Yaris (hatchback) with about 102,000 miles on it.

The horn is not working, and I am wondering what the cause could be?

I am trying to fix it with my friend who is a mechanic on leave due to family issues. He has over 10 years of experience, but of course, has not fixed everything!

Here are some of the steps we have taken -

1)We changed the 10a fuse, the old one seemed fine, but we swapped it with a new one, yet no sound when I press the horn on the steering wheel.

2) The horn unit (located on the grill of the bumper works - we did this by connecting the horn directly to the battery of the car using an individual wire (not the green wire that is part of the wiring). Based on that we know the horn unit works.

3) When I press on the horn on the steering wheel, I can hear a click sound in the black color fuse box under the hood. I think this means that the fuse and relay are ok? And that there is a signal going from the steering wheel to the fuse box under the hood?

4) We opened the steering wheel, and could not identify any broken parts or loose contacts, but this was our first time doing so, thus it may be that we are missing something.

Here are some pics

At one point, when I pressed the horn on the steering wheel, it made a sound for a minute, but that was it.

I am thinking that the next step is to see if the 'tiny wire that feeds it is bad'...but I am unsure which wire it is, and how to access it?

Is it the green wire that is connected to the horn and goes to the fuse box (along with several other wires from other places) to the fuse box?

Or it is some other wire?

Any help that we can get on this will be very very very helpful!

Thanks,
desidude

 

[cabri]

Have you trued to bypass the horn switch

 

[desidude]

Hi cabri,

Thanks for your reply. How would I bypass the horn switch?

Can I still use the horn on the steering wheel?

Thanks,
desidude

 

[_Rick_]

I would check the fuse. If the relay switches, the horn works, then the fuse is the most prominent point of failure, short of a wiring issue, that you should check.

 

[desidude]

Hi _Rick_

Thank you for your reply. The fuse seems ok...I replaced it with the spare one in the fuse box. It is a 10A fuse.

I guess I could buy a new fuse and try?

I am hearing a clicking sound in the harness under the hood when I press the horn on the steering wheel, does that mean the relay is working?

Thanks,
desidude

 

[cabri]

Hi cabri,

Thanks for your reply. How would I bypass the horn switch?

Can I still use the horn on the steering wheel?

Thanks,
desidude

Bypass the horn switch on the steering wheel is only to determine if the switch itself is bad.

I would expect that there are only two wires attached to the switch.

Power in and output.
Attach the two together and see if noise is made.

If so, problem is in the switch itself which can be replaced.

Horn itself works.
You already replaced fuse.
Connecting wires together verifies the electrical path.
After that, the switch is the next potential culprit in the chain.

Switch can be replaced.

 

[desidude]

Thanks cabri

So would it be the single black wire, I believe that is the only wire that goes to the horn?

If so, how would we test this? I really appreciate your help.

 

[cabri]

There should be two wires to the switch

Another option is to run a hot wire from the switch to the horn input. If that works,there is a wiring issue.

 

[RLGL]

Anybody check the horn Relay?

 

[dbcooper1]

Yeah, sounds like the relay; if you hear it clicking when you close the horn switch, everything up to the relay is working. Likely the contacts aren't completing the path to provide sufficient current to the horn, which you also know is working. Sometimes contacts need cleaning or the whole contactor assembly get's crooked and doesn't complete the circuit; best to probably just replace the relay. If that checks out, look for a bad ground.

 

[pcgeek11]

I think that the Toyota horn switch is used to switch the ground connection for the relay coil. That is how my Tacoma is anyway...

If the Horn Relay is pulling in the switch is working. Either the fuse is blown, the relay contacts are not closing or the wire for power to the horn is open.

Since you say you replaced the fuse I would say Relay at this point. Swap two like relays in the under hood panel.

 

[Scarpozzi]

See if they have an answer in this thread:
http://www.yarisworld.com/forums/showthread.php?t=55259


Ok...for realz this time:
http://www.yarisworld.com/forums/showthread.php?t=40925

I'd just try tracing those wires back and look for any connectors that may be loose. Especially if you can find where they come from the steering column (look at wire colors) and go under the dashboard.

 

[sontakke]

On most cars, you can find bunch of similar looking relays under there. so do the substitution before buying new part.

 

[Danhawkins59]

I have a 2008 Yaris that the horn does not work. I can put a light tester in the wire of the horn at the bumper and press the horn switch in the cockpit and I get a positive flow. My tester lights up every time. So I changed the actual horn which did no good. Since I have positive flow all the way through it doesn’t make sense to change the relay. I don’t know what else it could be. Can anyone give me any suggestions?

 

[pcgeek11]

I have a 2008 Yaris that the horn does not work. I can put a light tester in the wire of the horn at the bumper and press the horn switch in the cockpit and I get a positive flow. My tester lights up every time. So I changed the actual horn which did no good. Since I have positive flow all the way through it doesn’t make sense to change the relay. I don’t know what else it could be. Can anyone give me any suggestions?

The horn is grounded through the mounting bolt for the horn. If you have 12 VDC at the wire then the horn should blow if it is properly grounded to the frame. Clean the mount on the horn and the chassis where it mounts.