1990 740 base

It's been happening for a while now, but once in a while, my "lamp out" light will go on when I'm braking, or sometimes when I'm signalling a right. I read once that the light-check system is weird in that sometimes not having matching bulbs could cause it. So of course, I try and replace all my rear lights, completely, (except the third brake light up top) and then lo and behold, it's STILL flashing sporadically. I think something might be a little messed up with the circuitry, because this NEVER happens when I have my headlamps on. If the lamp-out light goes on, I just turn on my headlights, and boom, the lamp-out light goes out. Does anyone have any idea?

Note: this car was in a flood submerged almost up to the radio deck at one point. Everything works fine, even the seat heaters. It's just that annoying lamp-out light.


Thanks.

First, are the bulbs the same Maker, Age in service, and Type.
Second, Are the bulb and sockets clean and shiny, if not scotchbrite.
Third, are the ground wire attachments to the body clean and without corrosion, especially since the car took a dip.
Fourth, is the ground lug inside the tail light assembly clean and shiny.
Fifth, Are the circuit board and bulb contacts good, Use a white plastic pencil eraser to clean without removing plating.
After all that, the red can relay could be loosing sensitivity, only way to know is swap out with a known good one.
(Above list compiled on my car from Boston)

wow, this is great, okay, i'll give all this a shot and see how it goes, especially the grounding thing.

thanks a bunch! i'll keep you posted.

Check and clean the electrical connections in all of the lamp circuits. Any connection that got wet is a good candidate for corrosion.