Two problems related to fog light switch have been reported for the 2005 Toyota Prius. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2005 Toyota Prius based on all problems reported for the 2005 Prius.
Both headlights will flicker and go out, mostly at different times than the other but can happen at the same time. By turning the headlight switch off, then back on after 10 to 15 seconds they will come back on. Driving on the freeway this leaves you in a very dangerous situation. Thank god for fog lights, a life saver at 70 miles an hour. This can also happen sitting in my driveway before leaving for work.
The headlight on the passenger side just turns off for no reason. I saw it off when stopped. It has done it several times after about a half hour of driving. It goes back on, but I keep the fog lights on just in case it happens in the dark. I think it could effect both head lights and cause a safety problem at night. I drive on unlit streets at night.