I have searched many threads and can't find anyone with the same exact issue. Hoping some X5 guru can offer some good advice. Here is the deal on wife's 03 4.4 X5. She first started getting intermittently for several weeks a "check brake lights" then she started getting another intermittent "check rear light". Nothing was wrong with the lights everything seemed to work fine, then her left rear blinker on the dash started rappidly flashing but the tail flasher would not come on. I just learned of all of this and started trouble shooting.

Here is what I have done.
-The left blinker light on dash flashes rapidly, the front blinker does the same but the read does not come on at all. Everything on right side works fine

- I first changed all three bulbs on left side which none of them appeard to be burned out and inspected for any corrosion or anything mentioned in the threads. There was no corrosion at all.

- Then I switched all three blulb and sockets one at a time from the right to the left. The two lower ones (brake and tail light) from the left worked on the right side but none of them from the right side worked on the left side. The top bulb and socket (the blinker) from the left one does not work on the right side. I felt this might be the problem but what can go wrong with the socket? There appears to be good contact with the bulb and within the slot it snaps into.

-Emergency flasher works on both fronts and right rear but not left.

I felt the left bllinker socket is the problem but then why does the working one (from the right side) not work when plugged into the left side?

Could it be a bad relay? If so does anyone know where the relay is located and anyone know the part # so I can replace myself?