I have a 95 quest and the tail lights are always on if the headlights or running lights are on. If the lights are off the tail lights work perfectly fine could this be a brake light switch or am I going to have to look for a problem in the wiring ?

SOURCE: tail lights and brake lights not working with headlights on

We had the same problem with ours, that is a Saturn recall items. Check with your Saturn dealer to see if it is still in effect. It use to make our headlight switch get hot. I think it was a poor ground in the taillight housing, I use to wiggle the bulb plug-ins and that helped for a while, but after the recall was fixed it never did it again.

SOURCE: 97 Caddy Deville--Headlights won't come on. Fuses OK

check blown body and / or lighter fuses 20A

SOURCE: Headlights don't work.

There is a circuit breaker inside the headlight switch body. It gets weak over time and use. The breaker is actually mentioned in the owners manual. A new switch is about $75.00 at the local parts store. You must remove the front of the dash to change the switch. Mine would go off and then in about 30 seconds reset and the lights would come back on. I would be driving down the road with my headlights flashing as the circuit breaker opened and closed. New switch = problem fixed.

SOURCE: 95' Buick regal, 3rd brake light works, tail

I dont have a diagram but the brake light switch has to feed the turn signal switch, Either that wire has a bad connection, or the turn signal switch is bad. Jiggle the turn signal lever and see if the brake lights try to work.