I recently installed an aftermarket stereo in my 99 blazer 4X4. About an hour after hooking it up, the dash lights went out. I replaced the headlight switch and shortly after, the dash lights went out again.

I did not hook up the orange or orange/white wires on the head unit. The factory harness was in good shape and uncut. I used a aftermarket connector to hook the h/u up. I'm stumped. What could be frying the dimmer switch? No fuse issues found.

 

What else happens does you stereo shut off? When the dash lights go out

 

I had a similar problem. Did you check if the wires were all plugged in behind the dimmer switch?

 

Just the dash lights go out. It is shorting something in the dimmer mechanism. Yes Matt, all connectors are plugged in. Only a single connector on the switch. No fog lights on this Blazer.

 

make sure you illumination wire on the aftermarket harness is taped/capped off, if not it may be grounding out, normally it would pop a fuse but I've seen them burn up switches before.

 

Update--I think it's fixed. I did not snap off the dimmer wire from the aftermarket harness so its possible it was grounding out on the stereo mounting cage (thanks jshultz). Also, I didn't trust the ground that is part of the harness so I ran a ground from the back of the stereo to the body.

All seems good now. It cost me two used switches (and one fuse), but found them on ebay cheap.