There's two fuses for the two power wires. One wire from the ignition switch turns the radio on, and one that's always hot is for the station presets and clock memory. The second fuse is probably labeled "lighter". On a lot of models, the memory circuit is tied to the "interior lights".
The reason the fuse popped is the lighter socket is not really designed for plugging in accessories. Even though they will usually work, the socket has special strips of metal that are being shorted out by the metal strip on the plug you're putting in. It all depends on the orientation. If you rotated the plug while the item was working, it would eventually hit the metal strip and pop the fuse. Because of the potential fire hazard, if the lighter element doesn't pop out on its own, there is a thermal cutout built into the back of the socket. If for some reason that fails, overheated parts will expand and touch that metal strip, shorting it out and blowing the fuse. It's a safety measure. Your plug is shorting against that strip.
Your options include using the power outlet, which looks like a lighter socket, but is labeled differently and doesn't have the safety features, having a power outlet installed if your van doesn't already have one, replace the lighter socket with a power outlet, or just be sure you always insert the plug the same way and don't turn it in the socket.
Friday, December 4th, 2009 AT 5:10 AM