Helping a guy with a 71 Duster, initially there were no dashboard lights. Most of the bulbs were burned out. Intermit problem with parking lights sometimes staying on, having to disconnect battery when parked. Changed headlight switch with a new one, now parking lights stay on, headlights work correct. Now dash lights won't dim, but the parking lights dim with the switch. Anybody run into this?

I'd start by pulling a batt cable then pull the bakelite connector off of the HL switch & ohm the circuits. www.mymopar.com will have the colors for you. Anything done up in the dash printed circuit area other than replacing the burnt bulbs?

Sounds like somebody jumpered something between fuse box and dash circuits, that shouldn't have been jumpered....

I had a similar problem recently. It turned out to bea mis-wired light socket, wherein a power wire was hooked to the ground or return wire. Only one socket was mis-wired but it caused all the lights on the circuit to incorrectly light.

Another possibility migh be the Headlight Switch, or perhaps wires that are shorted together.

Thanks for the suggestions. There is a three gauge panel mounted under the dash, along with a tachometer on dash that all have lights hooked up. The dash lights dimmed with switch before, changed switch and now they don't. The previous switch looks to have been replaced as well. Nothing unusual about circuit board. A few wires added to fuse panel though.