2002 Chevy S-10 lights

Bulbs for 12 volts should not burn out when 12 volts in applied, check around headlight fixture for any water leaks if any are present thats the problem. When lights are hot and water touches them they will crack. If its not the case get a volt meter out and check if your getting 12 volts to the head light plug. It should be 12 to 13 volts. Your truck should only be a 12 volt system. If there are two batteries hooked up you isolator box could be doubling volts to 24. If that is so disconnect aux battery and check again. Buy replacement bulbs install them be sure not to get skin oils or anything on bulbs they will last longer if you don't. There could be a chance they both blew because of just being old