I just finished a total top end overhaul on my truck and am ready to start driving it, but have hit a small snag. My state inspection requires among other things that the horn work. Mine is not. So I check the fuse, looks good. I pull apart the front and get to the horn. My Hayes Manual shows a blue and white and a red and green wire coming from the horn, one goes to the switch and the other looks like power. My horn has a third wire on the bottom which is not plugged into anything. It is a stock toyota horn but that third connector is not accounted for on the wiring diagram. I just wanted to see if anyone has the same unconnected wire on the bottom of their horn. If so, I can assume that the horn is bad and just replace the unit. I wanted to see what thoughts were out there before I blow money on a brand new horn when it was really a wiring issue. Does anyone know how to test the unit? Thanks for any and all info.

 

Make yourself a couple of leads to test the horn. Or get a Power Probe.

Give the horn 12V and see if it honks. If not, then bad horn(which isn't very common, since its a very simple unit. If it honks with you giving it power manually, then its something further upstream. I'm sure there is a horn relay, has that been checked/tested?

 

I don't see a relay on my diagram. Just a simple switch for the horn, which if I am reading it correctly simply puts the circuit to ground and works the horn. I will try to connect the battery directly to the horn and see if it works. If there is a short somewhere I have never troubleshot anything electric and the wire bundles on this truck look like a nightmare to get into. If you have any pointers as far as that goes I would greatly appreciate it. Thanks.

 

What exactly are you working on? Year, make, model, engine, trans, 2 or 4wd?

 

The horn grounds through the steering wheel iirc. Also, turn your steering wheel 90° and try push the horn button and see if it works. The inner contact ring could be worn out.

 

Good point, BBP. I've heard of guys using the brass from a .22 round to re-establish the contact from the button to the stationary ring also.

 

Yup. Which is what I'm going to do. Also, spacing the contact ring can be enough too.

 

It's an 89 with a 22r and a four speed. I'm going to try the jumpers on the horn today. I will also open the steering wheel and check the contacts. I put a multimeter on the wires to the horn and am getting about .3 volts constantly at the horn. I know close to nothing about electricity but that seems strange...

 

I jumped the horn and t works good. So I took apart the steering wheel and I see a green wire which looks like it should go to ground when the button is pressed. Unfortunately it is not. I have good voltage at the horn so this must be the issue. I don't seem to see the ring that gets mentioned. Does any one know which wire leads to the horn and what component is supposed to go to ground?

 

just for the record here in the great Salt Belt it is fairly common to have horns fail.

Then one must remember 20 or so years of winter weather.

The Part of the country makes a big difference.

 

My Haynes manual shows no relay on the schematic, but there shows one on the rockauto online parts catalog for my truck. Does anyone know where this relay is located and how I would test it?

 

Looking in the 88 EWD as I don`t have the 89 EWD it showed no relay.

They very well might have gone to one for 89.

Simple to check the relay as they most all have the contacts labeled just use a 12 VDC source to energize the coil then see if the contacts close when the voltage is applied.

 

Here is how I fix mine.
Copied...
Another thing I got fixed on my 91 was the horn. I know this happens alot and hopefully this will help some in the future. Pull the steering wheel with a Steering Wheel Puller that you can usually rent from a parts store for free. Then check it by touching the brass spring in the 11 oclock postion. I just used my wrench. If it honks it is most likely the brass ring on the back side of the wheel. Not the best picture but you should get the idea.



The way I fix this to take a small flat blade around the edge of the brass ring and raise it a little bit and slip some paper gasket under the brass ring. It has worn itself down and not making contact with the 11 oclock post.

Here is a better picture of the Brass Ring and my pointer finger is what makes contact to sound the horn. I just clean them with some fine grit sandpaper.




Got the horn to working. I used a .22 shell to make the contact to the steering wheel. I found this on Yotatech and like it better then how I used to fix my horns. I have it listed on my 88 4Runners build thread for more details about getting the horn to work on the first page.

 

Thanks Terrys87. That is an awesome write up and a huge help. I will pull the steering wheel when I get back home and try this out. I've got plenty of .22s if that's what I need to fix it...

 

Your welcome. That is the most common failure on these and a .22 shell works great. You will need to rent the steering wheel puller. If you try to hit on the shaft to get the wheel off, it will bulge and you wont the the wheel nut on.

 

I pulled the wheel and unfortunately no dice. The contacts are a little dirty, but it won't go even with using a wrench to bridge the contacts together. I got up under the left kick panel and I found a relay. I'm not sure if it is for the horn, as my schematic has no reference to a relay, but it looks exactly like the relay that rockauto lists as a horn relay for my 89. It is $20, so before I throw money at this thing, does any one know how I can test it? There are 3 prongs, it looks like 1 causes 2 to connect to 3. Can I put a multi meter between 2&3 and see if I can get 12 volts across it? Thanks for all you guys help. Since I have it off, I think I will still clean it up and add the .22 she'll that Terrys87 recommends.

 

I have replaced the relay and I have done the .22 trick and cleaned the contacts, still the horn doesn't work! This thing is driving me crazy. Does anyone know where I can get the wiring diagram for the horn on the 1989 yota? My Haynes manual is definitely wrong and the fsm I have is for an 84 which doesn't exactly jive with mine. Thanks