Hello all,

I've read a few closely related articles here, all which helped me rule out several possibilities. Narrowed it down and looking for the next area to investigate. Surprised at the number of horn not working results in google heh

As titled, my blazer's horn does not work. I've confirmed the horn does honk when hotwired, and the components of the steering column work by testing continuity through depressing the horn to the horn relay.

I'm focused on the three wires at the horn relay now which should be, 1 to the horn in the engine bay, 1 to the steering column and one always hot that should pass current to the horn wire when the steering column circuit is closed. It would appear the wire which is supposed to be always hot is dead, thus no voltage is sent to the horn.

So where does this orange hot wire come from? The horn's fuse is good, and does read hot 12v. I assume it's shared with something else which also is not working.

The fuse is labeled horn/dimmer I think. This could be either dash dimmer related, interior lights or both? as the dimmer can be used to turn on interior lights. So yeah, the interior lights do not work, nor does the dimmer switch (even for the dash lights). (Digital) Dash works, and when headlights are on, the dash does dim but I can no longer control the intensity as the dimmer dial is shot.

So I'm left thinking the horn isn't really the problem, nor the relay itself, it's just something else which is shared. Looking to find the other end of the horn relay hot wire I guess.

Thanks in advance.
Jason

 

Please find the wiring schematic for your horn attached below. The horn fuse powers the relay both in terms of the coil and the switched lead itself. I would test for power at the fuse and then test for continuity from the fuse to the appropriate terminal at the relay.

 

Thanx for the schematic. I had hoped it was that simple.

Continuity from the relay to the fusebox was good, so somehow that left only the fuse itself to not pass current. Fuse was good, as I swapped another just to see.

After standing there in disbelief, it finally came to me the contacts of the fusebox itself must have some oxidation or resistance. Used a boxknife to add texture to a fuse and insert/pull a handful of times as well as squeeze the contacts a bit with some needle nose to make it a tighter fit a bam, it works. Interior lights returned as well.

Oddly the radio which wasn't working came back on as well. This blows my mind because I thought the horn and the radio circuits were independant (Well the dimmer does tie into the radio, so maybe the radio decided to nosedive just for that). But confirmed it wasn't some curious anomaly by removing the horn fuse and the radio won't function. (It cuts on but no control except volume, just static/scratchy noise)
Tapes would play though, mixed with the static.

Anyhow, success for my initial issue. Next is to attempt to diagnose whether the radio is toast (2 of 4 speakers out, but only 1 speaker having infinite resistance from the connectors behind the radio) don't see how fixing one speaker will fix the other but stranger things have happened as my truck defies all logic sometimes.

 

Glad you got that fixed! This is not the first time I have seen corrosion in a fuse box.