1985 international flatbed. All lights work, except the right rear, does not blink when blinker switch is activated or the four way flasher, it has running lights only.????
Does the break light come on that side? Either have a bad wire or a bad socket, to find problems like this it is nice to have a test light to check for power, & finding bad wires.
as rowfast said...also check the grounds... bulb...if still nothing ..wiggle the turn signal switch...