I have a 99 S-10 Blazer and bought a new head unit for it.My problem is that I unhooked the factory head unit and seen that I need the harness adapter, I plugged the factory unit back up and now I have no power to anything(wont start, no lights ,heat,or gages) any thoughts? Thank you in advance.

 

did you check your fuses ?

this is why people disconnect the battery before messing with any wires in there trucks/cars
Just a future reference

 

I found the problem(bad ground wire on the batt.) Thanks for the input though.BTW I always disconnect the battery before any electrical work.

 

I had this problem too whenever my brother helped me get the subs put into my blazer, turns out he had just pushed the ground cable bolt back into the battery instead of screwing it back in.