automatic headlights on a 90 corvette

The 90 is a reversable motor. + on one wire & - on the other motors one way; swapping signals reverses it.

This will need a relay setup. In order to get the right relay wiring setup, you'll need to know if the headlights return a signal that tells if they are fully up or down. If they don't, don't worry, a different setup will still get the job done. PM us once you know about the headlights. We can get the diagram setup for you then.