The tail lights stopped working on my 2005 Prius. The manuals and dealer service department were helpful. Some advice would also have been helpful. Two things need checking. The fuse box and the light bulb. Fuses are located in a fuse box that is under the dash on the driver's side. You have to lie on the floor with a flashlight to find it. You have to remove a cover to reveal the fuses. The manual shows which fuse is involved for the tail lights. It is a 10 amp fuse located at the end of the assembly. A fuse puller is required to remove the fuse. A puller is mounted in the main fuse box in the engine compartment. The fuse box has a removable cover. The fuse puller is white and inserted into a special location described in the manual. The fuse can be checked with a continuity checker. I have this available on my inexpensive ohm meter (Volts, Ohms, Milliamps or VOM meter). In my case the fuse was OK. Next check out the bulbs. A cover can be removed from inside the back of the car in the corner where the rear corner lights are located. The tail lights are the lower of the three bulbs. The socket can be removed by a quarter turn counterclockwise. Without stressing the wires, slide the socket out enough to remove the bulb and after checking the bulb with the Ohm (VOM) meter replace with a new bulb as required. I found the bulb, #194, at my local auto parts store for $4.95 for two bulbs. The socket is replaced with a clockwise quarter turn and the cover is replaced by noting the way it is attached to the lining in the rear of the car.
Thanks for the post. I want to add that on my Toyota Prius, both tail light bulbs - both - went out at the same time! I only had one burned out tail light bulb on my Prius, but because one burned out, they both quit. Once I replaced the burned out one, the other one popped right back on. Some sort of safety feature? I don't know - I didn't see any info about this phenomenon when I searched for info...... Thanks again, and thanks to the kind guy who flagged me down to tell me - I had no idea.
When do you say "tail lights" are you referring to all the bulbs including blinker and stop lamps? I will agree that having the bulbs blow at the same time is not likely, but you can easily look at the bulb and see the status of the element. Also as you already have the trunk open, swap bulbs side by side.
My guess is that you have corrosion on the ground lead. This is the most common failure for a single light set. Chase the ground back to where it is attached to the frame and make sure it is a good connection. Do My Assignment For Me Also, clean the bayonet fittings for your bulbs to ensure connection. This is a good maintenance activity on older vehicles anyway.