Hey Doc or other helpful souls out there ...

'92 400e with some bulbs out. I unfastened the taillight assembly and found the following ... they are the same on each side meaning there are 6 receptables for bulbs EXCEPT the driverside assembly has an 8 prong pin with 6 of them wired and the passenger side has a 6 prong pin with only 5 wired. Long way of saying the driverside has one extra tailight. Is there some explanation for this?

I believe that is your rear fog light. To turn on your front fog lights, you pull the light switch out one click. To turn on the rear fog light, you pull the switch out a second click. At that time an orange circle in the center of the light switch should also turn on.

As I understand it, the rear fog light is about as bright as a brake light, and is intended to be more visible to the rear than the tail lights. There is only one of them, on the drivers side, to make sure there is no confusion with the brake lights. This is only what I have heard - the system is in place but not activated on my 87 300E.

I second that.

Thanks John and Shane ... found everything just as explained.Can't wait for the owner's Manual to get here ... lol.

That is definitely what the extra bulb is for. I have seen the same lighting system on BMWs and Lexus as well.

European drivers know about this system, but here in Texas, I get drivers pointing out that I have a tailight bulb out!