Just add blinker fluid in the left front tire, but careful to only add 3.14 oz of radio active DOT69 government issue blinker fluid. I you do not add corect amount you nuts will clack together as you walk away from your mav.
The turn signal in the cluster is for the turn signal option on European model Mavericks. The Commander has a kit you can purchase but the Maverick kit is not a available yet. If you look at the parts diagram you will see there is a turn signal lever switch mounted on the steering column.
That is interesting. I had the same thing happen on my old Commander after I put on new exhaust with a Power Commander. I never did figure out why. It was still that way when I sold it even though I had removed the Power Commander. Weird.