Horn Keeps going off. schematic provided

I hae a 1999 honda civic.  to make a long story short, what i wanted to do was solder a wire to the horn terminal inside the remote control module and when i hit the lock button 2 times, usually the horn goes off once...but instead of the horn going off i wanted to have the relay that i have hooked to the wire turn on while there is current goin to the horn and have it turn off when stops(we are talking a 1/4 of a second honk).   when I touch the wire thats hooked to the relay(the relay is grounded also) the horn goes off.  I can see that the battery is always connected to the horn coil and when i touch the horn lead to my relay thats grounded, it will make the horn relay go off, but also make my relay go off.  but i only want my relay to go off.  is there anything else that i can solder that wire to that will give me the 12v for just that split second when i hit my remote to lock my car?  Below is the schematic of the horn circuit.