1984 Chev P30 Motor home horn will not honk using the horn button replaced the relay, nothing. horn will honk bypassing the relay and horn button what to check next?

Probably the horn relay. Find it feel it clickwhen you press horn. Then run wires plus and minus to horn. It honks replace relay
Fuse, button, relay, horn. If not bad wires conectors.

You may have wires that have become crossed. The wire to the horn and a hot wire have probably lost the outer insulation and crossed each other causing the horn to start honking when it is connected. Check the wires with an electrical tester.

english please.
is car the Brazil HOmbre? ours is different. here. in USA.

we are USA english forum
horn is dead, 1997 Hombre.
check the fuse yet,that is always first, marked HORN it is.
a 20amp fuse.

the horn is very simple. but the path it follows is complex
(due to steering wheel turns, complications in all cars made)
first off is air bags if car has air bags , working on horn parts in dash will be dangerous, so defeat air bags first. !
the FSM book tells how to do that. read that. and do that.
be safe.
so you can test the horn on a battery, hot wired. just like a light bulb. same test. but why would both horns fail>?"relay"
clean the horn base grounds so its not rusty.
sure one horn rust, ignored then 2nd rusts and owner acts.
you can check the horn relay, or replace it.
the check the horn relay coil for 12vdc across the coil of relay while honking, 12vdc honking, if 0v, that means the horn switch in the steering hub is bad or the airbag, clock spring contacts bad (danger area)
the horn button grounds a wire. to energize the horn relay.
it only takes a volt meter to test all this.
got one?
other wise it's a gue$$ing game.

our car (USA) is:
"In 1996, Isuzu replaced its Pick Up with a version of the Louisiana-built Chevrolet S-10, the Isuzu Hombre, based on the Brazilian market S-10"

so will answer for S10.
this car has 2 horns if both are dead, check the relay

using a volt meter,
i honk the horn and the bottom of the coil in relay below goes to 0v
from 12v.
if its not 12vdc to begin i check the top of coil there.
if that pin is 0v, the fuse is blown, good looking fuse can in fact be bad. we test fuses. not guess.
if you honk the relay closes, (can be seen or heard to close)
click?
if the relay does click, then he bottom contact below goes to 12vdc
if not the relay IS BAD.
the below horns grounds are missing , error in the manual.
the horn bases are grounded. to the car body. if not they will be dead.

replace it from any reliable auto parts dealer.

The horn button in steering wheel is stuck in the "on" position. You have to open up the wheel and gain access to the switch and either repair or replace it.

check horn relay in engine bay fuse box

You may have a poor connection in the wiring to the horns or the grounding connection. The click you hear is the horn relay. Have someone press the horn button while you wiggle wires. Also try rapping on the horns themselves with a stick or screwdriver handle--if that makes them honk, the internal contacts may be bad. Replace them if that is so, as they are usually sealed. Hope this helps!

I replaced the horn relay which is located inside of fuse panel under the hood of car on the firewall, have someone push button to be able to hear a clicking sound coming out of the correct relay, then trade out relay of the same and see if horn works

You can remove the horn relay and use a Ohm meter and check the resistance between the horn relay connector terminal No. 86 (Black Wire) and ground. If the ohms are less then 5 ohms replace the horn relay. There are a lot more tests but as Polarcycle states you can do what he suggested other then I believe you have two horns in this vehicle.

I've had chev vans from 1977-89 ( I love those chev vans) and everyone I've had always had the horn/or horns if dual on either side of the rad(right if single left and right if dual)while facing the van from the front with the hood open on the motor side of the radiator support.