I have a 98 freightliner fl70. All the tail light functions work except the right brake light. The bulb is good but there is no power to the back for the brake light. Checked all the fuses still no luck don't think it's the brake switch cause the left brake light works fine. What about a relay? Any suggestions?

SOURCE: 98 gmc suburban brake lights

One of two things cause this corroded or poor chassis earth at the bulb holders or the circuit board that holds the bulb is faulty.

SOURCE: left side brake and hazard lights don"t work

sounds like a bad turn signal switch, wiggle it , just a little bit,... see if some of the lights start to work. do your turn lights work correctly??

SOURCE: rear brake lights don't work

you prob got a trailer plug prob bad wires if not tail lights run through turn signal switch tell fix ya bout me ok

SOURCE: all tail lights work except the left brake light,

No. Check wiring or socket.

SOURCE: tail and brake lights quit working

Auto light shut off is a relay that is basically a timer.
Replace it .