I have a 1997 Jeep Cherokee.

Starts and runs fine, dash works until i turn on the headlights then it goes dead except for the highbean symbol.

Also, with the headlights turned off, as soon as i turn on the A/C or Heat, which does not work at all, all the dash goes dead again.

So no Heat, No A/C and dash only works without head lights and A/C panel turned off...

Codes led me to believe i have a bad ECM, so i changed that. Checked the 3 grounds under the hood that are off the bundle that goes thru the firewall behind the dash...

I am lost, very bad at electrical stuff.

edited: Also, everything worked just fine a week ago, then this all began, nothing was done to it. I checked every fuse, all are GTG.

 

Have you traced the wiring harness ensuring it isn't or hasn't rubbed anything to make a break causing it to short or ground out? Fine cuts in the wiring will also cause an issue as looking quickly you don't notice it unless you're actively flexing the wire giving it a thorough look over.