I'm not sure if anyone else has had this problem or not but here goes.
The display on my stock AC delco radio would suddenly go black, sometimes it wouldn't some on when the truck was turned on, other times it would just black out while driving. I though I just had to live with the problem but my wife (gotta give credit where credit is due) found out the if you turn the high beams on (while in DRL mode, ie. lights off) the radio display would come back on. It works everytime (for me at least), and hope this thread can help others as well.

 

Wow, that's weird, then again I have witnessed some of the weirdest electrical problems with Blazer/Jimmys.

 

Sounds like a wire is shorting out have you tested the wiring?

 

haven't tested anything yet, found out the heated mirror switch turns on the brake lights (they work alright when turned off). I assume there is a bad ground or something somewhere but haven't gotten around to searching for it yet.

 

I have the same problem, the display will go off when the headlights are turned on. (high or low beams)

I take it that noone has found a solution?

 

oops! I double posted!