Help: Tail lights don't turn on with headlights!

[Artur555333]

There is something that is referred to as an "Auxiliary Under Dash Fuse Box".
I am not certain where it is exactly, but here is a figure that depicts it:

View attachment 20219
Here is a list of the functions of these fuses:
View attachment 20220
View attachment 20221

Note that F4 is the relevant fuse for the taillights, HOWEVER, it looks like a lot of other things would also be out if this fuse were bad, so unfortunately this is not likely to be your problem. I posted this information mostly for general reference.

Thank you this helped although in my 2018 clarity PHEV it was caled fuse "n" instead of "F4"
IT IS UNDER DASHBOARD. If you dont have auto seats adjustment. There is 2 empty slots insted of 2 20amp fuses. And 2 7.5am fuses. Buttom 7.5 fuse was blown. After flooding craked DRL on top of other 10 amp drl/ac fuse under the hood

 

[yantaq]

Thank you this helped although in my 2018 clarity PHEV it was caled fuse "n" instead of "F4"
IT IS UNDER DASHBOARD. If you dont have auto seats adjustment. There is 2 empty slots insted of 2 20amp fuses. And 2 7.5am fuses. Buttom 7.5 fuse was blown. After flooding craked DRL on top of other 10 amp drl/ac fuse under the hood

Thank you all who started this thread and the replies. mine is fixed after replacing the fuse "n" -> "SMALL (7.5A).

TLDR:
I had the exact same issue of taillight not coming up (later found out about marker, and license plate as not working) due to a small fender bender on passenger front side.
my 2019 clarity had a fender bender and got it fixed in auto body shop but failed to catch the light not coming up issue, which I realized after few weeks of driving when someone behind alerted me about the taillight not on.