This may seem like a dumb question, but I've had multiple friends call me who were following me to tell me my taillights were out. I changed all the bulbs and verified that each bulb illuminates:
turn signal light
reverse light
brake light.
I think the same bulb that operates as the brake light operates the running lights. It's a 2-fillament bulb and one maybe illuminates as the running light and 2 as the brake light.
I took it into the dealership and they said nothing was wrong with them. It's just frustrating b/c I can't really see behind me when I'm driving at night so I don't really know what's going on back there.
My question for anyone w/ an outback sedan, model 2005 or later is, are your running taillights pretty dim??
