Taillights out

It could be the bulbs. Try replacing them.

 

it's the harness. when you see prii running around on the streets you'll notice the rear right one goes out first... i messed around with my clip enough where mine usually doesn't go out anymore.

i've seen the passenger light go out.. or "short out".. or lack of connection i guess... anyways.. it goes out first, it seems.

open the hatch, pull the plastic covers off, and fiddle with the harnesses.

 

For the driver's side, open that cover to get the jack and you'll be able to access wires for taillight. Try to move them around. That should be better than banging.

 

+1 on the wiring harness. Simple to fix, but a PITA to get too sometimes. If your prius is still within the factory warranty, take it back to your delearship and document the problem. Good Luck.

 

I've got the same problem with my driver's side tail light. Last year the brake light wasn't working due to a faulty LED. Fixed for about $35. Now, the same light is having taillight issues, similar to those mentioned in the original post. I haven't had time to fiddle around with it yet. I've gotten a lot of people to tell me the light is out though.

 

I finally got a chance to wiggle the tail light wiring harness. As soon as I touched it, the light came on. It's still on.