...also, at some point, if you keep getting lights out in the rear, check the boot that runs from body to trunk lid...wires get fatigued there from all the cycles of opening/closing. I've been in 4 times or so for various lights.
I'd had a taillight out and did pull power from my other side, but that only lasted a year or so...then the others started going.
BTW, if the light isn't out, but the indicator is still on, you might check some other lights that'd give you the same signal (as a rear light)--namely, license plate lights, reverse lights, and whatever the lights in the lid itself are called...probably just rear running lights.
Upcoming NYC dates: Jan 8 and 27. See Facebook for other shows and PM me if you can make one...love to see you there!
Mangofy your E46!