Ok, heres a question about the electronics of an 89 LX 5.0 Mustang.  My turn signals won't work.  They don't even try to.  The bulbs are good, a friend and I tested all the wires to see if there were any loose, disconnected, broken, or in anyway unfunctional and there weren't that we could find.  I bought the manufactures manual to try and solve the problem but it doesn't help at all that I've seen.  Anyone know of any probable solutions?  I want to say its a relay or switch thats messed up but I can't find any that control the turn signals besides the obvious one on the steering column but that working fine.   

My 2 guesses would be either the multifuction switch inside the steering column as you had stated....or the turn signal flasher in the fusebox.

Mr86GT

Yea, try the wiring in your steering column, not where the light switch is, the one under the steering wheel.  This fixed my problem.  My signal lights woundn't work, my AC or Heater, and my temp gauge didn't work either.  See if you 4 way flashers work,  If so its probally not in the actual signal lights.  Good luck  

I had a similar problem with my '89. Turned out to be the flasher relay in the fuse panel. The funny thing is, the relay was mounted in the back of the fuse panel, so it was not visable from the front.(?) This was probably a freak thing, but anyway a $3.00 part solved my problem.