Horn Not Working

[RBLACAUSA]

That's awesome, hopefully your frustrating conundrum will help others in the future, I hope you can return the expensive parts you bought!!

Thank you. Yes, I'm old school, learned much from forums the past 20 yrs so the few times I can give back, I do. I'll have to eat the $100 relay so now I have a spare, but the the other stuff was Prime and will be returned.

 

[JonnyMuck]

FIXED IT!

It ends up that the horn on the left side (when standing in front of the engine and facing in) has two wires feeding in to it. The horn on the right has only one wire feeding into it.
The two wires on the left horn are: one feeding power into the horn connector, then one feeding power back out of the connector and into the horn connector on the right.
In short, the two horns are wired in series and NOT parallel, despite what I read elsewhere, maybe here in T4R somewhere.
Even though we tested the wires for continuity from the relay socket to the connectors to both the left-side and right-side horn connectors and got zero reading, we didn't realize that there were two contacts that we should've tested at the left-side connector. We were about to run a new wire from the relay to the horns when we decided to test for continuity one more time and had the epiphany when I must've touched the second contact while manipulating those wires and got a reading.

From there it was downhill. Simply open up the loom to expose a little more of the wires, cut off the bad connector for the left-side horn and solder on a new 1/4" female flat spade receiver and voila.
We probably could've figured it out if we had a signal tracer and I actually ordered one yesterday but hasn't arrived yet. Oh well. Glad that's over with. It ate up most of my weekend.

So, after 22 yrs of service, I'm guessing road vibrations (the horns vibrate on their single bolt mounts) caused the input wire to become disconnected in the connector.

Thanks for doing this. Im running into the same exact issue with my '07 SR5. Except, when i checked the voltage of the two horn connectors to the horn, it is not out putting the full 12V.

I can also hear the relay click when pressing the horn button from the car.

Toyota really made it a pain to change out the horn relay under the dash.