hi all I'm randy new here to this forum. bought a 2001 blazer for my daughter's boyfriend back in October 2016. truck had leaking heater core, he had it replaced by a friend. since then, fuel gauge doesn't work, temp gauge doesn't work, all idiot lights on, battery doesn't charge properly, sometimes needs a jump. has new battery and REMAN alternator. I took an instrument cluster out, took a peek around did not see anything obvious. I did notice a plug hanging by the park brake pedal and do not know where it goes. see picture attached. Any ideas would be VERY helpful, as this thing is a P.I.T.A.

 

 

Not too sure on the plug, but someone will soonish...

first time I did my heater core, later found out i didnt have to, i had problems with my heat and no dash power what so ever. Turned out I didnt hoom up the heater control plugs and vacuum lines correctly, and I didnt tighten the screws on the 2 main plugs.
after I put it back together the second time, worked like new...

 

Nvm on the plug comment, didnt notice how old the thread was...