I kept finding a dead battery in the morning and did not realize until after I replaced it that the tail lights are staying on. Not sure if that's what kept draining the battery. This is on a 2010 Volvo XC90 3.2 liter. Anybody have any ideas. By the way, I got a check brake light warning light a couple days ago and replaced it. Didn't help though.

 

I would think it's really your brake lights (not taillights). Brake lights are powered all the time, even with the key off, etc. If the switch doesn't take them out, like it's supposed to, they'd just be on forever.

I don't have a 2010 XC90 but on most cars this could easily be caused by a very simple problem.

 

Here's a strange update.
So, after checking all connections, wiring harnesses, etc.
All I did was replace a faulty rear brake light lamp which was failing intermittently.
Immediately after changing the lamp, the tail lights (not the brake lights) but the lights above the brake lights remained on even while the vehicle was off.
I drove home and after turning off the vehicle, all lights now went off.
I beginning to wonder if the failing brake light bulb was somehow shorting out the relay or control circuit.

 

In case someone comes to this. Mine did same but when the boot did not close properly then the rear light stays on. Although the tail was shut with the button but it did not close properly.