'05 Prius taillight wire harness connections?

all,

Well I just had to do my first expensive un-scheduled maintenance/repair in 5 3/4 years ( sheesh, maybe I should get rid of my Prius before it gets too expensive to keep on the road---only joking, of course, guys). I had to fork over $4.99 (@ Auto Zone) for a blister-packed pair of #2825 bulbs for my right tail light.

The tail light on an '05 Prius is divided into 4 segments : the darkened multi-LED brake light at the top, the amber turn signal light next, the back-up light next, & lastly the red tail light (using a clear #2825 bulb) at the bottom. The tail light, back-up light, & turn signal light are all bulb sockets that twist to un-lock & remove from the tail light assembly, but with 4 segments in that assembly, why are there 5 wiring harness connections to the back of the unit??

The top-most connection to the multi-LED brake light feels like (I can't really see it) a simple push-on connector block & as I already said, three of the other connectors are twist-to-lock bulb sockets. BUT there is another connector (the 2nd one up from the bottom) between the tail light socket & the back-up light socket (where there appears to be NO bulb in the assembly). I thought it might be for light that might be somehow channeled out to the side reflectors, but none of my 6 reflector segments in the rear (2 on each side & the bottom ones on each side) throw any light at night. They are JUST reflectors & nothing else (unlike the upper reflector in the headlight unit that doubles as a side marker light that actually contains a bulb).

This 2nd-one-up connector seems to feel like (again, I haven't looked that closely because I didn't think I had any other burned out bulbs in that tail light assembly) two separate, slightly bendable prongs (attached to the tail light unit) that might hold a ridged connector (with the ridge sliding into the groove between the 2 prongs). I did not try to remove that connector to investigate (for fear of breaking one of those plastic prongs that this extremely cold weather might make too brittle) and again, I don't think I have any OTHER burned out bulbs in either tail light unit.

So, has anybody tried to remove the connector I'm talking about & is there any bulb in it that might possibly channel light out to the 2 side reflectors?? If not, why a connector there & what would a bulb (if there is one) be for, if not for that. Thanks for any insight any one of you can offer.

Ken (in Bolton,Ct)