I have a rather strange problem. I have a 1993 pickup, 22re and the horn is not working when I press the button on the steering wheel. At first, I thought this was a worn contact inside the steering wheel, or perhaps a bad horn.

However, the horn does work when I jumper it directly to the battery. Moreover, I'm getting 12v at the horn connector when I press down the steering wheel! Nonetheless, it won't work off the connector. I also double checked the ground.

This is rather confusing, obviously. I know the horn draws a lot of amps (e.g., it arcs when jumpered to the battery). Is it possible that the steering wheel button does send 12v to the horn, but for some reason can't get enough current to flow? Any ideas appreciated.

 

Switch activates the relay, relay sends power to horn. Check the relay.

 

Thanks for the tip.

So you're thinking the relay may be 'partly' working, sending a bit of power to the horn connector, but not enough amps to actually work the horn?

Also, the relay is behind the driver's side kick panel, correct?

 

Did you search, "Horn troubleshooting"?
Really? Are you sure horn has 12V to it only if, and only if, you press steering wheel horn button? I don't think so.
If it's anything like the first-gen 22RE, there will be no relay (bad design that i will fix on mine). There will always be 12V at one side of the horn. Pressing the key button on steering wheel will connect it to ground.

 

@RAD4Runner -- I suspect you are thinking of an older setup, where (if I'm understanding correctly) the horn had two wires coming in. This is a 93 pickup, there is only one wire coming into the horn connector, the ground is provided by the body where the horn screws in. And yes, I am sure that that one wire has +12v if and only if the steering wheel button is depressed.

 

I was thinking exactly what RAD4Runner was thinking..... until I found a schematic (wiring diagram) for a 1993 Toyota Pickup.

It looks like Toyota changed the horn circuit design so your 1993 truck DOES have a horn relay. According to the schematic below, the horn button in the steering wheel still completes a path to ground, but instead of grounding the horn itself like the previous generation, it grounds the coil side of the relay. Then the relay completes the power (12V) side of the horn circuit. The horn should ground through the mounting bolt. The schematic isn't the best quality but it is what I found.

 

AAH! Good! Toyota actually fixed that poor design on first-gen.

Based on the schematic above, the relay contact actually sends 12V to the horn (not through the flimsy steering wheel button anymore).

Yes, possible that there is high resistance between battery and horn, OR between horn and ground. Without load (horn disconnected), you will still get 12V at horn connector. That will drop when high-current horn is connected.
Suspect connections (see my signature), wires, the hazard fuse (black rectangle in schematic?), corrosion/dirt on connectors.

Quick Check: Remove hazard/horn fuse, inspect, test, clean contacts, swap with nearby fuse with same rating, etc.

To Verify With Multi-meter:
Measure voltage between ground and positive horn terminal, with the horn connected. You should get 12V there when u press horn button. If not, trace the circuit back toward the battery until you see where you see 12V.

 

I also suspected the fuse and replaced with a brand new 15A one -- no luck. Cleaning the connector and ground also didn't help.

I also tried this and you are right --- I did not see 12V anymore with the horn connected. There must be too much resistance in the relay or some of the other wiring. Traveling now, but in a week I will replace the relay and report back. Thanks for all the help.

 

More likely poor connection, like corroded socket, brittle and corroded splices, or relay that's vibrated loose from its socket.
Have a safe trip and a Happy New Year. Just don't take the truck to NY City without a functioning horn - LOL!
BTW, if you know any updated info on the La Bajada Switchbacks near Santa Fe, please share. I was hoping to drive that on my Route66 trip last year but I did not have enough info nor company.

 

how about just opening the steering wheel again, and try earthing the contacts in the steering wheel to a know good earth first. Sometimes the earths in the dash become ˟˟˟˟ty.

 

TBH, the drivers in Santa Fe are much worse than the ones in NYC. I'm tired of yelling out of my window ;-)

I actually had not even heard about La Bajada until you mentioned it! (moved here recently) From reading around, it seems that its on tribal land, and the tribe closed off access a few months ago.

 

It did turn out to be the relay. I replaced it with a Beck/Arnley one from Rockauto (part # 2030138), less than $10, and everything works fine now.