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How about in an 87 4Runner. I've tested the horn itself(working) and the padded horn switch on steering wheel(working).... Now I'm told it's either the spring loaded contact under the steering wheel that maintains contact as the steering wheel is rotated or the horn relay. I'd like to find the horn relay first as I'm told the contact is a pain to deal with.
You can replace the brass ring from the dealer. I am almost sure there is no relay. If you can take a wrench and touch the steering shaft and the little ring around the steering shaft and it beeps, it is in the button and the spring and brass ring. I use a .22 shell over the spring. I have changed the spring but it takes some finesse as there isn't a whole lot of room.
Below is copied from my thread.
Plate horn contact part # 84312-20011. $4.98 through an online Toyota discount parts dealer.
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.
Testing horn
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.
My newly-acquired '89 Base Pickup is hornless. I have redone the contacts and leaf springs inside the wheel (it is the 4-contact 45-04 configuration, NOT the 1-contact 84-01 with the plunger). The connected contact plate arcs to the steering column, so I have power. The hazards work, so it's not the fuse. The horn blows when jumped directly, and the modular wiring plug is solid. That leaves the relay, right? IS there a relay, and if so, where is it?
The horn blows when jumped directly, and the modular wiring plug is solid. That leaves the relay, right? IS there a relay, and if so, where is it?
It is likely the relay or the wiring from the relay to the horn given the diagnostics that you have done so far.
The relay is at "Junction Block #1" which is by the drivers left leg. The relay socket has 3 pins. Pin 1 should have continuity with ground when the horn button is pressed. Pin 2 should have + battery voltage at all times, even with the key off. Pin 3 goes to the horn. If you apply battery voltage to Pin 3, the horn should sound.
It is likely the relay or the wiring from the relay to the horn given the diagnostics that you have done so far.
The relay is at "Junction Block #1" which is by the drivers left leg. The relay socket has 3 pins. Pin 1 should have continuity with ground when the horn button is pressed. Pin 2 should have + battery voltage at all times, even with the key off. Pin 3 goes to the horn. If you apply battery voltage to Pin 3, the horn should sound.
Thank you. Junction Block 1 is there behind the kick panel. But it looks little like the diagram. The only relay I can find at JB1 is the Tail Light Control (Marked B in the diagram). There appear to NOT be either A (Back Up Relay) or C (Horn Relay) at this location. Am I reading the diagram wrong--does C not plug directly into the RH side of JB1? Or are those lines supposed to signify wires?
Thank you. Junction Block 1 is there behind the kick panel. But it looks little like the diagram. The only relay I can find at JB1 is the Tail Light Control (Marked B in the diagram). There appear to NOT be either A (Back Up Relay) or C (Horn Relay) at this location. Am I reading the diagram wrong--does C not plug directly into the RH side of JB1? Or are those lines supposed to signify wires?
Thanks! You'll make a mechanic out of me...
Actually it looks like your model year does not have a horn relay. I initially thought the '89 models had one.
The older trucks use a ground side switched horn with no relay. When you jumped the horn directly, did you ground the green wire with the red stripe to get it to sound or did you put + battery voltage on the blue wire with the yellow stripe and depress the horn button?
What I did was remove the horn entirely, and jumped it directly off the battery with the bolt bracket grounded at the radiator support. Is this stupid? The result was a tiny bit of spark, but no blow and no click. After getting it out, the horn's disk looks a little bent. See, Photo: Bad Sign?
Since you know your stuff (and I've heard this horn is WEAK at 108dB), do you know if Toyota made a better horn with the same modular plug? I might just buy that and not have to cut any wires.
What I did was remove the horn entirely, and jumped it directly off the battery with the bolt bracket grounded at the radiator support. Is this stupid? The result was a tiny bit of spark, but no blow and no click.
I thought you said you were able to get it sound in your previous post. The earlier horns ground though the electrical contact, the later models (with a relay and only 1 wire) ground through the horn itself.
Try this...
The electrical connector that connects to the horn should have 2 wires, a blue/yellow wire and a green/red wire. Use a jumper wire to connect the blue/yellow wire to the electrical contact on the horn that it normally would be connected to. Then use another jumper wire to connect the remaining horn electrical terminal directly to ground. The horn should then sound. Be careful not to short the jumper wires, you will blow the haz-horn fuse if you do.
If the horn sounds during this test, you know that everything upstream of the horn is good, and that the problem is somewhere downstream.
Also, do you own a multimeter or a test light?
Last edited by rustypigeon; 02-09-2017 at 02:44 PM.
Well, the wire-end of the plug is clocked 90 degrees, so it's impossible to be sure which terminal goes with which color wire. So I tried jumping it both ways. One way did absolutely nothing. The other way resulted in a very tiny spark, and the horn clicked faintly. Is it now reasonable to conclude it's a bad horn?
That test tested everything upstream of the horn itself. It means either the horn is bad, or the wiring upstream of the horn has high resistance.
To be certain it is the horn, you can take a 168 or 194 bulb from your sidemarker or license plate light and bend the wires out to make a test light. Stick the wires inside the horn electrical connector and have a helper press on the horn switch on the steering wheel. If the bulb lights up nice and bright, you definitely have a bad horn unit. If the bulb is dim, or does not light at all, you have wiring issues (possibly in addition to a bad horn).
168/194 bulb, bend wires out straight to make testlight...
...Then get yourself a real testlight for future troubleshooting. It will make things much easier.
Last edited by rustypigeon; 02-09-2017 at 03:48 PM.
Thanks. I owe you big time. I've decided to replace the horn myself, and if it still doesn't work, it's to a real mechanic I will go for the wiring.
Considering there is no relay, will any old horn do, or should I just replace it with the OE? Ideally, I'd like a louder/deeper horn with spades to match OE modular plug. Is there another model Toyota that had this connector and a better horn?
Many of the aftermarket horns require you to splice into the wiring. The OE horns will save the hassle of messing with the wiring, but they are about $65-$75 from the dealer. That is why I recommend you test the circuit with a test light as described above. I don't buy parts unless I am 100% sure the part is defective.
Regardless, if you do get one from Toyota, you can get either a "high pitch" or a "low pitch" horn. I don't think one is louder than the other, just pitch differences.
Good advice. Will any aftermarket horn work on this circuit without a relay? There's a WOLO dual horn that's <$40 that is loud, a decent tone and gets good reviews. I don't mind splicing if it will work.
... So I tried jumping it both ways. One way did absolutely nothing. The other way resulted in a very tiny spark, and the horn clicked faintly. Is it now reasonable to conclude it's a bad horn?
IF you jumped both wires DIRECTLY TO THE BATTERY and got no sound then horn is bad.
However, you still need to verify that the switch circuit (as Terry illustrates and Rusty Pigoen suggests )above is good.
No, I don't have a meter.
Next only to our senses, the multi-meter is the most important electrical troubleshooting tool for our trucks. HERE. No excuse for not having on.
Originally Posted by Kaleo1
Good advice. Will any aftermarket horn work on this circuit without a relay?
Originally Posted by rustypigeon
Yes. The horn just needs 12 volts. It does not matter if a relay supplies the voltage.
Originally Posted by Kaleo1
..., it's to a real mechanic I will go for the wiring.
One reason that the horn contacts may go bad is because they carry the all the current to energize the horn. If you're going to a REAL and GOOD mechanic, ask him to wire the horn with a relay. This will not only hep save the contacts, it will also ensure that you have less power loss over the wiring and more power getting to the horn.
Check out the Crown Victoria horns at the junkyard I heard they are good. (two-tone).
11-11-2015, 11:38 AM
