I have a strange problem. When I turn the headlights on, the dash lights and radio display light goes out. Any ideas?

Thanks in advance

 

Bad ground, or a short somewhere. Check the headlight switch first. The earlier trucks were know for having problems with them. (melted switch and connector....)

 

That issue was supposedly resolved in 99 with the rotary switch. Although if you run low dimmer a long time it gets very hot.

Pull the bezel (carefully) and then the switch is just a couple screws. You'll see all the wires and connections there.

 

Well put me in for idiot of the month award, the problem was the wheel dial for the dome,cargo light was set too low.

 

You're not an idiot, we've all been there! Glad it was nothing to fix.