1997 Toyota 4Runner replacement horn doesn't work

Tiny
TLP32!
  • MEMBER
  • 1997 TOYOTA 4RUNNER
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 147,000 MILES
I am trying to replace the stock horns with something better-sounding. I removed the old horns from the brackets, snipped the wires, attached new wire connectors and clipped them onto the new horn terminals and then mounted the horns. Because I think I was supposed to mount the new horns THEN attach the wires, I may have blown something. The horns don't work when I press on the center of the steering wheel but I hear a very faint horn sound as I take my hand off of the wheel. I've adjusted the screws that change the horn tone but that had no effect. The 10-amp fuse under the hood is good. What else should I check?
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Monday, May 17th, 2010 AT 2:55 PM

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Tiny
CARADIODOC
  • EXPERT
Hi tlp32. Welcome to the forum. How many wires were on each old horn, and how many terminals on each new one? Do you hear a relay click when you press the horn button?

Caradiodoc
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Monday, May 17th, 2010 AT 5:27 PM
Tiny
TLP32!
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Yes, I hear a click from inside the dashboard below the steering wheel.

Regarding the number of wires, there are two horns. The one on the driver's side had a plug w/ two wires and the passenger side horn had a plug w/ one wire. The horns I bought both have two terminals. I put female plugs on the two wires and attached them to the terminals. On the other horn, I did the same thing w/ the one wire and, as instructed by the directions, attached the included wire to the mounting nut and the other end plugged onto the open terminal.
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Monday, May 17th, 2010 AT 8:13 PM
Tiny
CARADIODOC
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Hmm. Seems weird the plugs would be different on the two horns. Have a helper press the button, then measure the voltages on the four horn wires. On each one, one wire must have 12 volts and the other must have 0 volts. Leave the wires plugged in when you make the measurements. I'll look for the results tomorrow afternoon.

Caradiodoc
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Tuesday, May 18th, 2010 AT 3:05 AM
Tiny
TLP32!
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You said to measure the voltages on the four horn wires but there are only three: two on the driver's side horn and one on the passenger's side horn. I need to buy a voltage meter so I'll do that today.
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Tuesday, May 18th, 2010 AT 8:24 AM
Tiny
CARADIODOC
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You actually do have four wires now.

"as instructed by the directions, attached the included wire to the mounting nut and the other end plugged onto the open terminal."

That's your fourth wire.

If you already have a test light, you can use that instead of buying a meter. If you have to buy something, there are a lot of inexpensive meters out there for under 5 bucks that work just fine. Look for a Harbor Freight tool store or something similar. Most of the traveling tool sales have the same thing and they really do work. If you go to someplace like Radio Shack or Sears, don't get suckered into buying a fancy auto-ranging meter or some other features you'll never use. You just need a basic voltmeter that will measure up to around 20 volts max. Most will go to 1000 volts on different scales but that isn't important for working on cars.

Caradiodoc
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Tuesday, May 18th, 2010 AT 2:09 PM
Tiny
TLP32!
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I followed your instructions for testing the horn wires and got no reading for any of them. I grounded the black meter clip to the truck frame and told him to activate the horn when the red probe was on each wire terminal -- no reading. To ensure that the meter wasn't defective, I tested the car battery and I got the normal readings.

Thoughts?

FYI. When the horn was activated, I still heard the clicking of the relay and a very, very faint and short horn noise.
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Monday, May 24th, 2010 AT 4:16 PM
Tiny
CARADIODOC
  • EXPERT
Hmm. Gotta have 12 volts to make the horn do its thing. Use a pair of jumper wires to connect one of the horns directly to the battery. It should squawk. That will prove the horn is not defective. As for the missing 12 volts, I suppose it is possible there is a second fuse for the horn current, but normally the same circuit is used that makes the relay click. On normal circuits, when the relay clicks, current travels from the battery positive to the horn fuse, to the relay, through the switching contact, through the bulkhead connector on or near the firewall, and to the horn connector. Somewhere along that path there is a break. If you can follow the wires according to their color, work your way back while measuring at various points. You're looking for that missing 12 volts.

Common suspects are corroded or broken wires at the connectors, (unlikely in this case as it would only affect one of the horns), a corroded connector pin at the bulkhead connector, or most likely, pitted relay contacts, particularly if one of the old horns was shorted and drew heavy current.

Caradiodoc
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Monday, May 24th, 2010 AT 6:33 PM

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