1999 Buick Regal. Instrument panel lights will not come on when we turn on the headlights. The dimmer knob is turned correctly. I’ve checked all the appropriate fuses (I think). The radio display is also affected. The time display almost completely dims out. This even happens when the headlights come on automatically at dusk. Please help!!
First of all, review your owner’s manual to make sure you are not forgetting something about how the dashboard controls work. Second is to turn the dimmer all the way in one direction, then the other, and do this several times. If it is a rheostat type, the wiper (the part that moves along the resistor) can get oxidized, and moving it back and forth a few times can wipe off the oxidation.
Most likely this is either a blown fuse or a faulty dimmer control (the part on the other side of the dashboard the knob turns). There’s a very slight chance it is a loose connection. Unlikely, unless someone has been working on something under the dash recently.
An auto-electric mechanic with wiring diagram in hand can tell you what part is wrong without too much billing time I expect. With a little luck, maybe somebody here has the answer.
Be sure to check the tail lights, sometimes they share the same fuse.
Has an after market radio been installed recently?