Dash lights off when headlights are on

[TurboJoeD.]

The backlights in the dash work fine all day long. But, when I turn on the headlights the backlights in the dash go off. This is a 4cyl/V8 swap 93coupe. I haven't had any alarming wiring problems or anything. Point me in the right direction to start looking for a problem please.
This might be related but I doubt it: my tach doesn't go below 2500--I don't think it is accurate after 2500 either.

Thanks for any help.

 

[jp89chargedgt]

I would start with the dimmer switch and work from there. I had one go out and would do that. Just a guess though.

 

[crazy04mach]

+ 1

You can also check your headlight switch..

 

[Prime Lord]

My money is on the dimmer as well. Check around on eBay before you buy a new one though, because they're not cheap.

 

[TurboJoeD.]

I will check the dimmer switch. I hope you're right. I have already checked the headlight switch and the multi function for functionality and loose wires, burnt connectors, etc. I'll find a dimmer
Thanks