LED lighting systems, mounting configurations, and light fixtures are disclosed for original and retrofit configurations. Some configurations mount the light fixture with a mounting bracket that allows for the removal and replacement of the light fixture in about the same time as a traditional light bulb change. Some configurations provide for fuse removal and replacement without the need to dismount the light fixture from its mounting bracket or without the need to open the housing of the light fixture to access the fuses. Some configurations use a battery backup system and self-check methods with LED light fixtures configured for public transportation applications.