I just installed a new headunit in my 2001 blazer zr2 with the wiring harness and antenna adapter and everything.... there were 2 plugs plugged into my factory headunit and i dont know what to do with the other plug. I think it may have something to do with my speedometer and tachometer because there stuck now... speedometer at 100mph and tachometer says engine is revvin all the way. Is there another adapter i am supposed to get that i missed? thanks for the help

 

I left the other connection you are talking about open. Check your fuses you probably blew one installing the head unit, it happens.