I checked the stop lamp fuse and it looked good. I haven't been able to check the bulbs because it's beginning to rain. It's kind of hard to imagine both going out at the same time. The tail lights don't come on when tou turn the headlights either in case I didn't make myself clear. I leave my light system in auto and they both come on together when I start the truck. The only thing I've done recently is plug in a trailer and hauled some things, not sure if it's related. I guess I'll try the bulbs beforing going out and buying a ground tester. The bad thing is, I've got to take it to the garage this afternoon...lucky me.