And they're often burned out or not grounded properly when you people get a new-to-them Bronco. The ground issue pops up after one's been sitting a long time or in a moist environment.
If you're still young and flexible, you can twist your head up under there and pop the bulb sockets out to inspect/replace the bulbs. Just removing them and putting them back in will sometimes fix a connection issue, but in extreme cases, a separate ground jumper wire can be fabricated to mount between the instrument cluster housing and the body.
The screw holding the Constant Voltage Supply aka IVR (instrument voltage regulator) is a good spot on the cluster, and the body/firewall is a better ground than the dashboard itself.
Of course, that's just one of my long-winded ways of saying... "Turn the switch until the lights come on." or a reasonable facsimile thereof.
Then again, a bad headlight switch or wire can do it too. See? You just can't have too many possible explanations when it comes to Broncos!
Paul