2003 Ranger. 4.0 front blinkers work ok. rear blinkers not. turn either side on both sides blink. with headlights/tail lights on depress brake all rear lights turn off. with headlights off depress brake brake lights work. Have replaced flasher unit and on column multi selector switch, oh and rear bulbs. Remove both rear bulbs check socket with test light everything works correct. plug in either bulb check remaining socket all of the problems above.??