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How the horn works, Horn Troubleshooting - First-gen 4Runner
How the horn works on First-gen 4Runner (1986, 1987, 1988, etc)
Horn Troubleshooting. Verified on 1986 to 1988 22RE.
This is one of the quickest ways to narrow down a horn problem, AFTER YOU HAVE USED YOUR SENSES (see, hear, feel) to inspect the system. ABSOLUTELY NO NEED TO TAKE ANYTHING APART. JUST VOLT DC SETTING ON THE MULTI-METER. (An assistant may be needed).
Horn connector for 1986 22REliable is here (1988 wire colors are different. I do not know about 1987):
1988 schematic is shown below (1986 notes and wire colors in parentheses):
HOW IT WORKS:
There is always 12V at Pin 1 of the horn from the hazard-horn fuse (15A) when good battery is connected well.
Horn button on the steering wheel connects pin 1 of the horn to ground, making it sound. In the steering column, a metal ring and a sliding contact keeps one side of the horn switch connected to ground (I believe Terrys87 has a write-up on this)
HERE IS HOW TO TEST IF CIRCUIT UPSTREAM OF THE HORN IS GOOD (when steering wheel is removed):
When horn and horn circuit are working normally, expect these:
Muti-meter to Volts DC, 10-Volt range (if not auto-ranging)
Negative (black) probe to clean, bare metal body ground, Red probe to test points in red.
12V Always means connected to power run "A" (red wire-blue stripe. There is always power there when connected to good battery, regardless of ignition switch position.
When Pin 2 (Green wire with red stripe) is shorted to ground, horn should work.
REPEAT: When horn and horn circuit are working normally, expect the above. Tell us what your system is not doing and what makes it different from a working one and we'll go from there.
Last edited by RAD4Runner; 12-14-2021 at 02:47 PM.
I need more Coffee all those arrows are confusing !!
LOL! Coffee coming up...
Then when the horn is open what readings does one get ?? I know and I know you do .
Above describes ALL voltages to expect on a normally-functioning horn system.
Why does anyone ever test a horn circuit that works ??
I did. To help others who may have a horn that does not work (and to help me plan my upgrade to louder, dual-horn with a relay to protect the flimsy horn contacts on the steering column.)
In order to troubleshoot one needs to understand how a normally-functioning system works and ask:
What it is supposed to do but does NOT?
What voltages are supposed to be there but are NOT there?
Then maybe this is only the first installment of all you ever wanted to know about Horns??
Correct. I could not possibly describe all deviations from normally-functioning horn system. That is the job of the one with the problem.
Last edited by RAD4Runner; 01-31-2022 at 10:45 AM.
I am curious about your future dual horn upgrade....
Yeah... plan is put a relay exactly electrically in place of the stock horn, so the relay gets a switched-ground control (thru horn button). I will re-route wires, of course, so relay will be as close to battery as possible.
Then relay will power stock horn AND a plain Hella that cousin gave me. If thats not enough, the relay circuit will allow me to install pretty much any horn upgrade. I heard Crown Vics' dual-tones sound good?
Originally Posted by dropzone
Ray you are gonna need to just mount a coffee maker permanently on a swing out mount for your truck!
That would be a cool mod - LOL!
Last edited by RAD4Runner; 11-05-2017 at 10:27 PM.
I just found out that the 3rd-gen 4Runner has nice low-profile horn... as in no actual "horn"... but it sounds pretty good. Low-profile will allow more mounting location choices.
I am tracking the problem with my horn now...main problem is that it is not working. First, I think I will need to go into the steering wheel and see if the contacts are working okay.
Thanks for the posting!
... First, I think I will need to go into the steering wheel and see if the contacts are working okay.
No. First is read my signature; put us in front of your engine compartment.
Second, read the posting above about properly functioning horn and see what's different on your horn. [/quote]
I am sure you will post your mod when you finish it. My horn works just fine but I don't like the sound.
Thanks for putting up these "How-Tos" and Troubleshooting threads. They are nice to refer to in the future!
Ditto on all that. I recently heard my horn, not intentionally, and was like WTF was that.
Originally Posted by RAD4Runner
Yeah... plan is put a relay exactly electrically in place of the stock horn, so the relay gets a switched-ground control (thru horn button). I will re-route wires, of course, so relay will be as close to battery as possible.
Then relay will power stock horn AND a plain Hella that cousin gave me. If thats not enough, the relay circuit will allow me to install pretty much any horn upgrade. I heard Crown Vics' dual-tones sound good?
FWIW, in looking over horn options I read that Lexus horns are a significant improvement over the stock ‘flattened Roadrunner’ sound.
Re Crown Vic horn aren’t those activated differently than the Toyota grounding activation situation?
I have bright shiny metal awaiting your bright shiny upgrade.
Originally Posted by RAD4Runner
LOL! Coffee coming up...
.
Coffee in the AM – good (but make mine decaf). Bacon in the AM – great I’m right behind you on the chow line. But, beans . . . in the AM? Whoever is hiking up that mountain behind you is gonna need oxygen before y’all reach the 5000 foot mark.
Ditto on all that. I recently heard my horn, not intentionally, and was like WTF was that?
I have bright shiny metal awaiting your bright shiny upgrade.
On my 1986 22re had a horn problem as it would only work when the steering wheel was upside down.My friend took off the cowling and found a broken soldering point on a wire and the round contact plate was bent.Soldered the wire back on and bent the plate and a functioning horn.
On my 1986 22re had a horn problem as it would only work when the steering wheel was upside down.My friend took off the cowling and found a broken soldering point on a wire and the round contact plate was bent.Soldered the wire back on and bent the plate and a functioning horn.
Makes sense, Dave.
If you tested with multi-meter (as shown), at position where horn did not work, Pin 2 of horn would have stayed at12V or near it....
Does the red-green wire from pin 2 run directly back to the steering column? I have 12V at pin 1, but nothing at pin 2, and when I short the steering wheel switch I still get nothing. I unplugged the horn and wired it straight to the battery and it works, and the post button in the soft steering wheel cover works. PO did some serious magic on the wiring harness, so I'm trying to figure out if I can trouble shoot the ring steering column switch by shorting it instead of pulling off the steering wheel. When I short the green red wire in the steering column harness to ground, I still get no horn. Making me suspect that I don't know anything about the steering column, or that I have a broken wire somewhere. (I needed to get a much longrr jumper wire to test continuity from steering column to horn connector. Would that even work?) Thanks!
Thanks for the rapid response RAD, you're the best. Also, I forgot to mention in my first post that I am working on an '87, so it seems that the wiring colors that were posted for the 86 also apply to the 87, just in case anyone else comes looking for that later. Wire colors at horn connector
Originally Posted by RAD4Runner
Yes, as schematic shows.
Pin 2 right at the horn connector? Should not not be if your horn is good.
I wasn't able to test at the horn side of the pin, but in the connector (where G-R is attached) I do not have 12 V (testing with the horn connector disconnected form the horn.)
Originally Posted by RAD4Runner
How did you know it works?
Disconnect G-R wire from horn Does it get continuity to ground when you press horn button?
So I have found that this is where the problem really lies. I did some more work on it this morning, and found that when I pulled the steering wheel and shorted the spring loaded pin to body ground, I got continuity between Pin2(G-R) and negative terminal at the horn connector.
I reassembled the steering wheel and did NOT get conductivity when pressing the horn button. So I pulled the steering wheel again, pulled the brass ring and cleaned it up, and tested continuity on the ring switch by shorting the blade conenctor that comes through the steering wheel to the same body ground in the cab and looked for continuity with ground at the horn pin 2. No luck... So that MUST be the problem.... (keep reading...) I didn't have a .22 brass lying around, so I found something else that I thought would be the right size an a decent conductor. I know that this is not a long term fix, as the abrasion will likely wear through, but I broke the end off of a buss fuse I had lying around, picked the glass out of the cap and slapped it on. Voila, now I have continuity from the spring terminal switch to the blade on the front of the steering wheel no matter where I turn the steering wheel. This is where the happy ending should normally go, but alas, the horn switch still doesn't work. Used the other end of this fuse as a terminal repair to the "spring switch" for the horn in the steering column. Fuse end cap installed on the "Spring switch"
I tested the push button in the horn cover by looking for continuity between the blade terminal connector and the frame of the push button cover, where it rests on the steering wheel, and I get good switch action from that system, so that switch works, now the ring switch works, and I've confirmed that the wiring is all OK between the steering column and the horn connector. So the real problem I am having, is NO GROUND AT THE STEERING WHEEL. As best as I can understand it, the push button in the steering wheel is supposed to connect to ground through the plate in the steering wheel itself, back down the actual steering column, but when I check for continuity between the big plate or the big nut in the steering wheel and the frame ground, I get nothing. There is a tiny bit of unpainted steering column back behind everything closer to the dash, and I get continuity to ground there, but not in the actual steering column. Is there supposed to be some sort of wired ground to the steering column? Or is there something in my steering column that is just crazy dirty and preventing me from getting ground at the steering wheel plate? I'm hoping I don't have to pull apart the entire switch assembly and whatnot on the steering wheel, but maybe that's where I'm at.
Originally Posted by RAD4Runner
How about shorting EXACTLY terminal 2 of the horn that G-R wire connects to to ground?
Now that I have all the switches working, I wired in the horn and shorting from the blade connector in the steering wheel to the body ground gives me squeeky mouse ball action, so I really just need to figure out how to restore ground to the steering column.
Sorry for the novel, TLDR; Fixed the ring switch contact with a fuse terminal cap and some cleaning and now all switches in the assembly work, but I don't have ground in the steering wheel which is why the horn won't fire.
I seem to have posted a bit too quickly, and after some more fiddling and wire brushing, it seems like my ground to the steering column is intermittent. It is working now, hopefully it will stay working. Now that I have the wiring at least mostly figured out, it's time to add a relay (using RAD's upgrade) and these guys!
11-04-2017, 09:45 PM
