I've noticed a relatively harmless, but particularly annoying issue has cropped up with my 2004 Mercury Monterey (more-or-less identical to a Ford Freestar of the same model year). Normally, I turn on the turn signal prior to making a turn/lane change/etc. (because I'm a decent driver), and the turn signal turns itself off after I turn the wheel to straighten the vehicle once I've finished turning.
From what I can tell, there's some sort of sprocket/spring system linked to the steering wheel that pulls the turn signal stick back into the central/off position once the steering wheel turns in the direction opposite of what the turn signal indicates.
However, this mechanism now seems to activate the opposite turn signal instead of just turning the first one off. For example, if I put on my left turn signal, turn left (turning the steering wheel left in the process), then turn the wheel right to straighten the car out, the left turn signal will turn off and the right turn signal will turn itself off.
This car has already had a stupid number of problems in its 10 years of existence (including, but not limited to, a recalled torque converter, a water-damaged engine computer, another water-damaged engine computer, a bad anti-theft module, a faulty canopy wiring harness, and other maladies) - we probably could have gotten it replaced under Lemon laws if the problems were actually dealt with when they cropped up. I'm hoping this is something free/cheap/easy to fix that can be done at home.
Can anyone provide insight as to why this might be happening?