Bad socket? Bad ground? Problem in steering column switch?
yes and no
Check the fuses and the bulbs.
because that what they are for. otherwise they would be orange headlights.
Perhaps you need to check a fuse.
No. Daytime running light can be disabled without affecting turn signals.
The lights on your Buick could be out for a number of reasons. It could be blown fuses, faulty wiring, or dead bulbs. Your mechanic would be able to test this.
Check for a bad ground
I always start with the basics.......fuses. Then go to bulbs...... Look in your fuse panel and see if you have one marked tail lights......and check it. the brake, headlights and signals work off another circuit.
if the headlights work it is bad wiring if they dont its a fuse
Most likely a fuse or a bad ground.
Blown fuse(s) or short circuit somewhere ?
More than likely a defective Flasher Relay. Replace it.