tcatlin

Hi All,

I just moved from AZ to MA and now I need to see if I can get my 87 Toyota 4x4 Carbureted 22R to pass inspection. I need to get the horn to work in order to pass inspection.

15 amp fuse under hood is good.

I have power at the horn, but it's on all the time regardless of ignition switch or horn button pushed.

Not getting any power at the horn buttons on the steering wheel: blue wire between the two buttons and red wire to attachment point through steering wheel to column. Not sure where to look from here.

Don't see a fuse associated with horn under dash.

Any help is appreciated.

Thanks,

Tim

Hadmatt54

Japanese autos are wired differently than North American. Typically N/A vehicles have power from the fuse to the switch, then when the switch is turned on power flows to the apparatus and then on to ground, this is known as "switched power".
Japanese have power from the fuse to the apparatus, then to the switch and in this circuit when the switch is turned on, the power flows through the switch to the ground, this is known as "switched ground"
Your horn does not work off of the key, it's on the same circuit as your hazard lights (4 Way Flashers) and is hot all the time from the fuse to one side of the horn button, as I explained above. If your horn is good (the coil inside is not open or shorted) you should read battery voltage or close to it on both wires of the horn (on an 86 it would be green/white from the fuse to the horn and green/red from the horn to the horn switch not sure if your 87 is the same) and you should read battery voltage at the horn switch. Your coil isn't shorted or you would be blowing fuses, but if you are not reading battery voltage on one side of the button then it's probably open and you need a new horn! A quick test is to take the horn off, put a wire from the source terminal to the positive of your battery and put a wire from the other terminal and touch it to the negative, if it's good it will blow!

tcatlin

OK. That makes sense now. I did buy a new horn. Hooked it up but did not work, but I don't think I checked the power at the wheel with the new horn in place since I didn't have this understanding of the system. All I have is one of those 6/12 volt lights that look like a little screwdriver.

So one line from the blinker is always hot, the other returns to the wheel. Pushing the button completes the circuit by making a ground. That makes sense. Thanks!

I'll hook the new horn up again and test for power at the steering wheel.

If I still don't have power to the steering wheel with the new horn, could this indicate failure of the relay?

I can see that the spring pin is making contact to the brass ring. Thinking I should clean it with scotch bright to make sure it's a good contact. also cleaned off the contacts at the buttons as they looked dirty.

4Crawler

iTrader: (3)

The horn switch in the steering wheel is a switch to ground, as noted above. You'll not see any voltage there. What sort of horn did you get, an OEM replacement or some generic aftermarket one? Factory horn will have 2 wire terminals, one for power, one for ground. Many aftermarket horns will have one terminal for power and the ground connection is via the screw attaching it to the vehicle. Might be the wiring under the brass ring has broken or pulled loose.