Is it an after market alarm system? If so, check to make sure your battery is connected good. I have a viper alarm system on my s10, and I went to put a system in it, when I hooked the battery back up, it would go off. That sucked, cause it was loud as hell and would scare me, and i'd jump and have to put it back on, :blah2: so u might check all your connections. :dunno: