2012 Yaris horn and hybrid battery filter

[craggle]

Hello all

I don't normally post here as I'm a Toyota iQ owner but my partner owns a 2012 Yaris hybrid, very nice it is to drive too...

Recently the horn has stopped working. She told me it had packed up so I went and pressed the steering wheel centre and after a few tries it worked again but now no amount of pressing will get it to work. I have popped the top of the front bumper off, found the horn and connected a volt meter to the cable and sure enough, no voltage to the horn. A jump cable from the Battery to the horn connector does make the horn sound. 

 Is there a horn relay in the car? My iQ has a relay but I can't find one in the handbook or in the under bonnet fuse box on the Yaris. If there is no relay, I guess I'm taking the steering wheel apart to check the switches and the steering wheel "clock-spring" mechanism? 

 

One more thing, does the hybrid Battery in the Yaris have a cooling fan and a filter?

She owns a horse and anyone who knows anyone with a horse will know the car is used like a pickup truck carrying feed, hay and all other sorts of dusty stuff about. Sometimes in the summer the engine revs high for prolonged periods which I think is a Battery overheat symptom although no warning lights have come on yet. I have found an air intake under the rear seat but haven't found a filter in there yet? 

 

Does a PDF workshop manual exist for the Yaris. I have one for the iQ, proper Toyota thing, works as an interactive PDF through a web browser. Be great if I could get one of those for the Yaris.

 

Many thanks

Craig.

[TonyHSD]

Hi

the horn issue is likely from the steering wheel. It could be the clock spring or something more common is the contact plates. You need to remove air bag and clean the aluminium base where contact plates touch it and you will be ok. 
Search YouTube Auris horn fix and you will see. 
Hybrid Battery has no filter but a grill and doctor that need to be clean and if they are dirty best to dismantle everything around and clean all parts including Battery cooling fan . Again in Auris forum there are some posts 

Good luck 

[craggle]

Many thanks

Just found an Auris horn video and it looks nice and easy so I'll give that a go first thing. Didn't think it would be just a static blade contacting the ground, all other cars I've seen have a lead with a spade connector on it to make that connection. 

I'll give it a good clean and maybe add some dielectric grease to the contacts.

Thanks also for the Battery info. I have found the intake with the grill over it and I do try to tell her to keep that clear but I suspect there is a fair bit of dust got in there over the years. Maybe a job for the spring to take the covers off and clean everything including the fan blades.

Thanks again for your help

Craig.

[Bernard Foy]

What you do re the horn is not an immediate issue. But if I were you I would attend to cleaning the cooling fan and area ASAP.

[Stobie]

have a look at this for the battery New toyota yaris cross hybrid battery technical review - YouTube

 

[flash22]

Yes the Mk3 has a fan on the Battery, No filter just a mesh screen to clean (behind the passenger side rear seat trim)

the horn is a simple circuit, fairly standard on most Toyota's

1 fuse feeds both control and supply, the horn acts as ground side switch

Just an example

KGB10 horn diagram.pdf

 

[craggle]

Thanks again all.

I found time yesterday to take the airbag off the steering wheel and have a look at the connections inside. 

All looks good in there. We have a wire that runs from the steering wheel clock spring type thing to a brass rail on the back of the airbag which then makes contact with three small stubs on the steering wheel providing the ground when pressed. 

Everything in there is clean and as it should be. I disconnected the cable from the back of the airbag and touched it straight to the steering wheel metal work and still no horn. 

I guess I now need to check if horn cable is providing a circuit through the clock spring and if it is, I'm not sure where to go from there. All the other steering wheel controls work fine and no airbag warnings on so if the clock spring has a problem, it is only that one circuit.

I'd still like to know if the Yaris hybrid has any other relay locations or if the horn relay is tucked away inside another electronic module somewhere? It isn't in the under bonnet fuse box. Assuming of course it has a horn relay?

[craggle]

Well, I found the horn relay. 

It's right underneath the fuse as part of the integration relay unit. I took the cover off that and tested all the relays in there and they all work, all the contacts are clean and they check out just fine with a multimeter. 

So the horn works.
The contacts inside the wheel are clean.
The relay is good.
The fuse is good.
The steering wheel clockspring thing checks out fine.

I'm getting to the point I may just run new wires and bypass the existing system!

 

Craig.

 

[flash22]

Circuits may test fine with a meter but may not be able to carry current

break the circuit down, does the relay click if you apply a ground at the control side of the relay

apply a ground to the connector under the steering column (usually a black wire) pin placement changes over the years it's pin 8, sometimes pin 10

Is the relay getting power to both the control and power sides ? Does the horn sound if you click the relay by hand, these integration modules like to crack joints (dry joints) also check the plugs and sockets for the green crusties

[craggle]

I found the time over the weekend to take the steering wheel off the car, remove the trim around the column and remove the rotary coupling / clock spring assembly. 

As shown above in Bob's photo, I discovered the black wire going into the rotary coupling was indeed the horn one. It had 12v on it when voltage tested and connecting it to a ground with a small jump cable made the horn sound. 

I circuit tested the rotary coupling on that pin and didn't find any pins at the other end that were connected to it so came to the conclusion the flexible track inside had failed in some way. I did open up the coupling but no obvious burns or breaks so I clipped it back together and found another circuit in the rotary coupling that was complete and had free pins at each end. 
I pulled the wires out the connectors at both ends, moved them to a new position in the plug and now it works fine again. 

I could have bought a new coupling thing but thought I may as well use a spare circuit seeing as there was two or three spare ones waiting there.

Craig.

[flash22]

The flat flex cracks right at the ends (or just beyond the glue/mount), usually the horn fails first then it will put an airbag light on

thanks for the update

[wildtapholer]

Wasn't there a recall around year about the horn failing.

[flash22]

17 hours ago, wildtapholer said:

Wasn't there a recall around year about the horn failing.

I don't think so (not for the mk3), just the Takata airbag recall