I a upgrading my horns on my toyota hilux invincible 2008 the kit comes with a relay. Does the existing horn circuit have a relay already because it is powering 2 horn already? or do i have to add this new relay ?

add a relay as the horn button will not carry the current for 4 horns

Hi there is no relay on the horn circut. And the airbag is a separate circut. It could be the airbag squib it is a cool of wire under the stering wheel that feeds the horn and airbag. Get it pluged in and diagnosed to confirm. Regards Jim...

hi Sewer10.
i have had a look on google images and there is some diagrams on there you might find helpful.

Check the Horn Relay (in fuse box under the hood). You will need to check for Circuit continuity between the Relay and the horn button. There must be a loose connection under the dashboard or in steering column. Pressing the Horn button Grounds the circuit, so check the circuit from the relay to the horn button for continuity to ground.

what country, ??????? horns vary by country some have 2 horns.
it can only be 4 things. on all cars. 06 Toyota Hilux?
to find it only takes a voltmeter, any DMM set to volts.
a horn, (or is ground at base rusty)
the wires. (that includes connections )
the horn relay if fitted (FSM read horn page,)
and lastly the horn ring in the steering column.
any or all, only a voltmeter can find all problems all the time.
the clock spring is AIR bags, you defeat them when working
on the steering wheel in any way shape or form or risk neck snapping.
RTM read the FSM, manual. its all there.
so is it at alldata.com

usa
the Hilux name was retired in 1976 in favor of Truck, Pickup Truck, or Compact Truck.
read the confusion here, for GEN 7 pickups.
http://en.wikipedia.org/wiki/Toyota_Hilux

see why i cant find yours,? tocama., tahoma or hilux.
as you can see, no COUNTRY NO JOY

or
my motto:
NO YEAR
NO MODEL
No engine. (or transmission type A/T or M/T?, if that is in question)
NO HELP (or your joy)

Someone would need to test the relay and the circuits it controls.
The horn pad grounds the relay to make the horn blow.

Your horn circuit is very simple. It consists of the primary circuit, which controls the relay coil and the secondary circuit that applies voltage through the relay contacts to the horns.

The Horn fuse (10 Amp) in the engine compartment fuse block supplies the battery power for both the primary and secondary circuits. This fuse is haot at all times (regardless of the ignition switch position).

Battery power is supplied to Pin 1 of the horn relay. Pin one of the relay connects to both the relay coil and to the secondary main contact.

The ground for the relay coil is provided via the GREEN/BLACK wire through the horn switch. If the relay is clicking when you push the horn button, then the primary side of the horn circuit is working.

When the relay coil is grounded by the horn switch, the relay contacts come together (that's what makes the clicking sound) and supply voltage to the GREEN/WHITE wire that connects to the horn assemblies.

Check for battery voltage at the horn when the horn switch is pressed. If there is no battery voltage present, then the only thing it can possibly be is dammaged contacts in the horn relay or the GREEN/WHITE wire is broken between the relay and the horn.

If there is voltage present at the horn on the GREEN/WHITE wire, the only possibilities are bad horn assemblies or a bad body ground that is not allowing the horns to ground properly. A bad ground condition can be verified by running a jumper wire from the battery NEGATIVE post and connecting it to the mounting bolt at the horn. If this makes the horn work, then you probably need to repair your body grounds near the battery.

is there 2 horns ? both need to be conected. check the ground, then check the wire in the steringwheel under the horn button it may have come off .and if not that then check the horn relay switch