Why does only one running light light on your 2004 solara when the lights are set on auto?

If only one running light is illuminated on your 2004 Solara when the lights are set to auto, it could be due to a burned-out bulb or a problem with the wiring or socket of the non-functioning light. Additionally, it may be an issue with the vehicle's lighting control module, which manages the automatic lighting system. Inspecting the bulbs and wiring for damage or corrosion can help identify the issue. If you’re unable to resolve it, consulting a mechanic may be necessary.