[JZiggy]

Hey folks,

I had the grille off my 2012 Sienna to replace the radiator and afterward the horns quit functioning. I went to troubleshoot it tonight and am at a complete loss. I would appreciate any ideas of input about this.

Here's what I checked so far:

Both horns measure 1.4 ohm and will sound when jumped to the battery
Both horn connectors get a healthy 12V when the horn button on steering wheel is pressed (key off or on)
Circuit diagram below. I inspected the P/I 40A and the ECU-IG1 10A fuses and they are fine
All contacts cleaned and sprayed with de-oxit
Finally, I tried plugging in a horn and jumping the ground direct to the negative terminal. Does not sound
I'm not 100% sure where the A1 and A2 grounds are but all the grounds in that area I can see seem fine.
I did not look for the horn relay. But based on the fact that I'm getting 12V I don't think that's the problem?

Thanks

 

[LenZ]

Follow Clinebarger's advice!

 

[jseyfert3]

But based on the fact that I'm getting 12V I don't think that's the problem

Odd. If you direct ground the horn, and then measure the volt on the positive terminal of the horn, do you get 12 volts when you press the horn and 0 volts when you do not?

 

[JZiggy]

Odd. If you direct ground the horn, and then measure the volt on the positive terminal of the horn, do you get 12 volts when you press the horn and 0 volts when you do not?

Yes, I tried that in fact.

If the system fails the load test, then what is the culprit? The relay? If so, where would I find it?

 

[paul r]

Close up the car . Set the alarm. Activate the panic button or do whatever it takes to get the alarm going. Just a thought really .What happens ? Horn sounds?

 

[jseyfert3]

Yes, I tried that in fact.

If the system fails the load test, then what is the culprit? The relay? If so, where would I find it?

Hmm. This doesn't sound possible. I think there's something I'm missing here.

When you measured the voltage, did you measure it at the horn, while the horn was connected? Where did your negative voltmeter wire go to?

Both horns measure 1.4 ohm and will sound when jumped to the battery

Can you clarify exactly how you jumped them?

 

[JZiggy]

1. I put one lead into the back of the connector (touched the lug crimped to the wire) and one lead to the negative battery terminal.

2. One jumper alligator clip to the input spade connector. One jumper on the mounting bracket (bare metal). Then jumper cables places direct to battery. Hope that makes sense.

Thanks everyone for chiming in here. There are a lot of good ideas for me to act on (once I can get the van back from my wife LOL)

 

[paul r]

I am not sure if there is a separate horn for the panic button. It may very well use the regular horns that are not working. There is nothing to lose if you try using the panic button to see if the horns work. The indicator lights should flash at the same time too.

 

[paul r]

Horn Won't Work-How to Troubleshoot The Horn on a 2004-2010 Toyota Sienna · Share Your Repair

Horn Won't Work-How to Troubleshoot The Horn on a 2004-2010 Toyota Sienna, a tutorial on how to track down the problem and get your horn working again

www.shareyourrepair.com

Could this be of any help?

 

[jseyfert3]

2. One jumper alligator clip to the input spade connector. One jumper on the mounting bracket (bare metal). Then jumper cables places direct to battery. Hope that makes sense.

Ah, okay. Sounds like you have a grounding issue then. If the jumpers work, but you get 12 volts on the input to the horn and no sound when they are installed, that would point to the mounting bracket not getting a proper ground. However, you did say in the original post that you tried plugging in a horn and jumping the ground direct to the battery, but it doesn't sound, so...

Can you just double check, measure either resistance from the ground of the horn to the battery, or measure voltage from the ground of the horn to the negative terminal of the battery. If the ground isn't good, the resistance will be high, or the voltage on the ground terminal will go up to some voltage (as much as 12 V) when you press the horn.

 

[JZiggy]

Update: tried the panic button. Lights flash and stuff but horns don't honk. I don't have a security system on it (which would come with an extra little horn).