How to wire a 12v 3 point car horn relay? - 1985 Toyota Corolla 2 Door

3rd post with year.
you can guess and replace all 3 parts and fail (wires bad)

use a voltmeter, and see if 12vdc makes it to the horn
it it is , the horn is bad, or not grounded
if not, the the relay, we can check that too with a voltmeter
12v across its coil means the switch is good.
12v not output from relay, with coil hot is a bad relay
easy huh?

as with all elect. fails check all fuses
in this case the 15 amp fuse marked, HORN
can i presume all else works good> car drives.?
all answers, USA spec car. nobody ever tells location, so..... if not USA< all answers wrong. the usa car has just 1 horn.....
got voltage to horn? 12v
Yes or no.?
if yes horn bad.
got voltage from horn relay
yes, bad wires.from, relay to horn
no, got voltage 12v to horn relay coil,
yes, good, no bad fuse.
got 0v to other relay coil (all tests honking)
yes, bad relay.
no, bad horns switch.

if you want me to guess. sure.
1: bad wires ../connections, end to end.
2 bad horn
3: bad relay
4: bad horn switch.

my guess, its a dead horn? both dead?
no actual question asked????????
the fuse is blow? in fuse box, eng. bay box.?
if no power to horn, (voltmeter)
we check power in and out of relay if there is one.
then at the horn button wire, (air bags can kill any mech. defeat them
first if heck bent to fiddly steering column parts in any why)
all this info is convered in in the FSM, get one. or login to alldata dot come. and read it.
here, ill look at yours. now.... a fast look.
ok 2 horns, hi/lo, and 1 relay in the under hood fuse box.
it should be labeled in the box, HORN
the relay can not work if the fuse is blown
or the horn enable line is dead. button.
the button grounds (0v) the relay via wire color lt.green-blu pin a11 on relay. if the a11 is at 12v the fuse is good.
if you push the horn button this A11 goes from 12v to 0v, and the relay energizes (click) and the horns both blow.
if no power makes it to the horns, the relay is bad no 12v
if by chance the relay output to horns go to 12v, then the horns are both dead.

Im having the same issue with my 6127, I wired it all accordly to the instructions and the horn is constant. Using the relay supplied, connectin pin 1 to 3 and 3 to constant 12v. Connect 2 to horn wire and 4 to + on the compressor. Negative on compressor to ground, and horn goes off? Not sure what to do

see the diagram attached.God bless you

all cars. it can be only 1 of 4 things, a volt meter finds this in 5min.
1: bad horn.
2: bad horn relay. (if car has it, some dont)
3: bad horn switch.
4: bad wires /conns to same.
to find this a tech uses a voltmeter.
he/she measures the voltage at the horn, if good, the horns is bad or not grounded.
if no 12v to horn (across it) when blown, you work backwards to the
point of fail.

Visually inspect horn make sure its not corroded and wiring is on it tight. Then use a voltmeter and when horn button is depressed 12v should register on the meter. If 12v are there and horn doesn't sound the horn is defective. If 12v does not make it there then its either the relay or clock spring (located inside steering wheel) most likely. A visual inspection should pretty much do it with the clock spring (corrosion ,wear of contacts). Relay must have B+ going to it at all times and coming out only when horn is depressed. good luck

Diagram should be on the inside of the fuse box or relay cluster lid/cover. If Test light has 1 wire and a sharp tip? Yes, but only if you push the horn button too ;-)

My guess is that the horn lost its ground, but you can check this with the light. The horn only beeps when both GROUND and Pos 12v are present. The horn button gives the relay 12v to close, and the relay gives the horn 12v to operate. The ground is always connected.

Connect tester clipwire to 12v source (battery, headlight (has to be on) and touch its tip to metal of car. Does it light? Good. the tester is working and the 12v is a good source.

Touch one of the 2 horn connection or wires (poke it thru the plastic - why tip is sharp). Does it light? Touch the other, does it?

If both light, (1 will be brighter) we can assume the horn coil is good and it is getting a good ground and I was wrong (it happens... but not often). The side that is BRIGHTER is the ground wire side.

Now have someone mash the horn button. Do you hear a tiny click? That is the horn relay. If not, look for the horn relay fuse and replace it. If you DID hear the click, the relay coil is good and is trying to switch 12v to drive the horn.

Now is time to locate and replace the horn fuse or the relay may have bad contacts. Look at the other relay part numbers in the cluster and see if there is a match for the horn one. Swap it out and try the horn.

Hope this all helps. To 'test' the horn, touch the dim side again anf listen for a scratching sound. That is the 12v going thru the tiny bulb in the tester (a resistance) and trying to drive the horn.

Good Luck!

no relay involved should find live wire behind head deck just get ur self a test light 12 bucks earth @ crimp end and needle point @ other with light up test the red or yellow cables with key off insure earth crimp is on chassis etc and push needle end on wires 1 should light up

Usually a wire straight from the fuse box, check the fuse box for a blown fuse, if this is not the case, follow the positive wire leading to the horn back to where it hits the wiring harness, it should tie off into another system, such as the interior lighting, radio, or cigarette lighter