My son has a 2001 integra. When the headlights are on, the dashboard lights and tail lights go out. Brake blinkers work. Any ideas?

. Check multi-purpose switch.

. Check the ignition switch for wear, pitting, or melting:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-46563-2.html#post224652