First thanks for all the replies. When this started it was the 1st. time I had a chance to use the bulbs. They are a 921 wedge type. We never hook up to shore power and everything else works as it should. They didn't all go out together. After the one died I tried a different one and moved the bulbs around resulting in the same scenario. At this point I put my original bulbs (incandecent) back in for the rest of our trip. I have a message in to the supplier and waiting for their input. This all started as a way of conserving my battery life, uggh. They are the wide range voltage bulbs.