Keyless Entry

Hello,

I have a 2001 Chevy Blazer 4-door 4wd. My question deals with the keyless enty system. When I set it the lights blink and when someone touches the truck the lights blink. How come the horn doesn't blow?????
If I hit the power lock button when getting out of the vehicle then hit the keyless entry and come back to the truck the horn will go off and the lights will blink. I have to get in the truck and start it before the horn will go off!!!

Is there anyway I can set it where the horn sounds when I lock the truck with the keyless remote and when someone touches my truck???

Thanks for any help