Factory disarm output pulse needs relay?

Hi all,

Please go easy on me if this has been covered in other posts, I looked for about an hour and a half and my question is still unanswered.  Also, if this should be common knowledge, then again, go easy...

On remote starters with a factory disarm/rearm (-) output pulse, why do they tell you to use a relay?  The pulse from the module will trigger the relay's coil, closing the pole and contacting the factory disarm/rearm wire to ground.  Why is a relay needed, the negative pulse from the module not adequate to actually trigger the disarm?

The reason I ask is, my car's OEM factory alarm has recently been going off at random times.  The ignition switch on my car had to be recalled, and when the dealer replaced it, they cut out the remote starter wires.  This I understood because they cannot support aftermarket parts.  I reinstalled the remote starter myself, using the old ignition switch harness that they let me keep.  The remote starter works like a charm, but the other night I armed the car and went to bed and I woke a few hours later to my horn going off.  The car is a 1999 Honda Accord EX, and the only thing I can find is that the disarm wire is not wired with a relay.  Although I am highly doubtful that this would cause the alarm to sound when the remote starter should be at rest.

HELP!

OK cool.  Thank you!  I'd like to keep the factory system, can't have too much protection I always say.  What about the relay for the factory disarm pulse?  What's up with that?

Thanks again!