Tail Light Bulb Problems

[AlK]

I have had a succession of problems with tail light bulbs recently. First the on-board computer flashed a warning to check the left rear turn signal. The turn signal bulb did not, in fact, light. But when I checked the bulb filament continuity, it was fine. I applied 12 volts from a power supply and the bulb lit. I checked continuity of the wires all the way to the control module under the driver's seat and all was fine. I didn't want to mess with the control module, so on a hunch, I replaced the bulb with a new one and the warning disappeared. However, the turn signal warning was soon replaced with a warning to check the rear fog light. In this case, the bulb actually lit when the fog light switch was turned on. So remembering the situation with the turn signal, I replaced the bulb with a new one and the warning disappeared, to immediately be replaced with a warning to check the rear brake light! Again, I replaced the old bulb (which was functioning) with a new one and the warning disappeared. Here's what I think is going on. The on-board computer has outsmarted itself. As any bulb ages, the filament electrical resistance increases. This changes the volt-amp characteristics, requiring more current be applied to maintain the same lumen output (at constant 12 volts). Apparently, the computer was programmed to tolerate a certain range of current and the old bulbs exceeded this allowed range, hence the warnings.

[dad911]

Not on a boxster, but on both my ford truck and a BMW sedan, I found jiggling the bulb in the socket would turn off the warning lights, and the bulb would work again, however, within a few months, the same bulb would actually burn out.

[randy_k]

You may wanna try a can of this and spray the sockets for the lights. It won't hurt anything and is great for all kinds of uses. You should be able to find it at a good electronics supply store. If not then online. Look for Craig Products/Cramolin R-5 Deoxit

Randy