Car Alarms: how to connect a relay for the horn to my alarm, automotive relay, constant power

Question
Hello.
I need help connecting a horn relay to my alarm. I tried with a 5 ports universal automotive relay but my horn wire is 12v and according to the diagram it should be connected to 87, 85 is a 12v, 30 is ground and when I test 86  is positive and the alarm requires it to be negative.
I dont understand how can I get a negative reading on 86 if I was testing and I found that 86 and 85 have continuity.

Answer
Well ok, tell me the make model & year of the car.
Most horn triggers are (-).

To test yours for polarity,
use a simple test light, ground the clip &
probe the horn wire. If it honks once you ground
the wire, simply use the (-) horn honk output
from your alarm an attach directly.

If however, nothing when probed, it is a positive horn
trigger and you would invert the (-) output from the alarm:

(85 & 87 to constant power - 86 gets the (-) from alarm,
30 to the horn wire. Nothing on 87a) The ground is added to this
as the trigger when you press the lock / unlock buttons.
(neg output, inverted to pos. pulsed for positive
polarity horns)

Try these set ups and let me know which
worked for yours.

www.RELAYHELP.com

ALARMTEK