tail light not working

I recently bought a 2000 sr5 and need to fix a few things in order to pass inspection. The last job on the list was the tail lights. From someone who doesn't know any better I assumed new bulbs were needed I replaced the upper bulb on the right and left the tail light. in the picture, you can see that on the left tail light the middle bulb and top bulb aren't working but on the right, only the top bulb is out. so figured its an issue with the fuses? But I'd figure I would post it up here before I do anything else.

Thanks

 

use a volt meter and see if you get power to each bulb socket. If yes then its the bulbs. If not then most likely just a fuse.

 

Exactly what he said ^^^

 

sockets tend to corrode as well .

I find a fitting brush is great for cleaning them