Left blinker problem
 

I just swapped steering columns in my 86 1/2T. Got the column in and all of the wiring reconnected. Headlights, brake lights and right blinkers work great. The left blinker, not so much. When I turn the left blinker on, the indicator on the dash does nothing and the front blinker does nothing, but the rear comes on solid and stays on. I swapped the bulbs in the front thinking maybe a bad bulb, but it does the same thing. Any suggestions on what to look for?

Re: Left blinker problem
 

I had a bad ground problem on my truck causing the same issue.
Clean ALL ground wire connections and make sure the ground tab in the socket isn't missing in action like mine was.
That missing ground tab caused a no ground problem.