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Horn not working - diagnosis?


My horn does not work. I checked for 12V at the horn connector and it does not get power when the horn button is pressed.

HOWEVER, I checked for continuity at the same connector and it seems to have continuity against the negative and POSITIVE battery terminal. That doesn't make sense to me.

Am I losing my mind? How can the horn wire connector have continuity to power when no one is touching the horn button?

I have read that there is a horn relay so I am going to investigate that next.

Edit: Hmmm and I just realized I can jump 12V directly to the horn to test it.

The horn button goes through the horn relay (because the horn draws several amps and will burn the horn button out) which I *think* lives next to the starter solenoid. Even with the horn unplugged you should hear it click when the button is pressed. It just connects and disconnects always-on battery voltage but I forget if that or horn B+ and the control side are fused.
You can test the horn by putting it directly across the battery.

The horn relay is indeed on the passenger firewall.  It's a three wire thing.  There's a pink wire which should be hot all the time, which supplies power to both sides of the relay, the switch and the load (most relays are 4 wire).  The gray wire goes to the horn button; when it is grounded, the horn relay turns on and supplies power to that black wire.  The horns have a case ground.  So you have a procedure:

- Ground the gray wire, bypassing the button.  If the relay is bad, you can...
- Put power to the black wire.  If the horns still don't sound...
- Put a jumper cable with power directly on the horn terminal.

If it still doesn't sound, the horn is bad, or the ground is bad. :)


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