Left Turn Signal never cancels out: WHY?
 

A month and a half ago I bought a 1981 Deville. The car is ok and the only thing it doesn't do as designed is cancel out the left blinker after the wheel is straightened out. The right turn signal works fine. Can this even be fixed?

I have to manually turn it off every time I finish making a left, I am accustomed to it now 6 weeks into owning the car but if I forget it the left blinker stays on making me look like somebody's senile old grandpa.

The reason the turn signal is not canceling itself is due to a broken turn signal cam inside your steering column. This cam is made of plastic and over time it gets brittle and breaks off. The part is relatively cheap in cost. To replace it is not so simple as the steering wheel needs to come off. That also involves disarming the air bag inside the steering wheel. I would definitely take it to a shop, if you want it repaired.

What about with no airbag?
 

Ok what you said sounds about right, but what if there is no airbag, the center of my steering wheel is about the size of a box of checks, I understand the wheel has to come off but is it any less tedious without an airbag to unhook and reattach? Pic for description

I have done the fix on a car of this era - no big deal. No bag to deal with (with bag disarm procedure is simple). You can find a exploded diagram of steering wheel here - just select your car in listing at left side of page. Big problem is finding parts for a car this old. May require ingenuity and JB Weld.

I believe you should be able to find the turn signal cancel cam as an after market piece on eBay. When I last checked, there was a fairly good selection -- about $20. Also, check with local auto parts store.

Sounds pretty easy to fix but it seems like it may open another can of worms I would rather not deal with, I already remember to turn off the left blinker manually so I can live with this. I am not too keen to dismantle complex stuff I am really not much familiar with.

I had the same problem with my 1999 Deville. O'reilly's had a cam for earlier models (ending with 1998) for less than $6.00, but none for the 99. I bought the part from Cadillac for about $50.00, and saw that it seemed identical to the one from O'Reilly's, so before I installed the Cadillac part, I went back by O'reilly's and bought one of theirs. It turns out that the O'reilly's part is ever so slightly larger (maybe 1mm in diameter) than the Cadillac one, but I tried it anyway. Works great. Took back the Cadillac part and got my money back.