When I select both the high and low beams with the all-in-one switch, the left high beam goes out and the truck stalls. Also, left blinker blinks rapidly. When selecting only the high beams, the left one won't go on. That bulb is new. So far all I've checked, with the multimeter, was voltages and continuity of the plug going into the left headlight housing. Both + wires had 12.5V; continuity in the ground wires was fine.