Remote Starter On 2000 Blazer

Hello.

I have a 2000 Blazer with a remote starter already installed.  When I bought the truck in May of 2000, the dealer had it sent out to have the starter installed.  They put a Black Eagle starter on it.  For nearly three years I never had any trouble.  But, back in January it started acting up.  Sometimes the starter wouldn't respond to the keypad and other times it would.  I changed the batteries in both keypads, but it acted the same with them both.  The LED's always lit when the button was depressed.  No matter how many times the starter didn't work with the keypad it always started with the key.

I decided that the remote starter went bad so I had a new one installed.  This time an AutoCommand remote starter was installed.  It worked flawlessly for a week or so, but then it started acting the exact same way as the Black Eagle acted.  Now, every time I use the keypad to unlock the doors the horn pulses.  The installer says that the horn isn't even connected to the remote starter.  The truck has been to him three times, but he can't figure out what the problem is.  Does anybody have any ideas for me?

Craig