It's either in the wiring but more likely in the turn signal switch (in the steering column) itself.
Check fuse Check bulbs--they are double filamented with the smaller for turn signals Replace turn signal flasher--Most common problem
I had the same problem in my 1999 Mercury Cougar, I replaced the flasher located in the blinker assembly. It was very simple to do. Flasher cost about $10
Perhaps problem in the steering column switch?
Check the flasher for the turn signals which is under the dash on the left side of the steering column . It is different from the emergency flasher.
I just had the same problem and found that my rear turn light bulb went out and the turn signals no longer worked. Check any of the turning bulbs. You may have replaced the hazerd light flasher. There are two flashers, the turn signal one is near the hazerd one under the dash.
I have the exact same problem as u in my 87 firebird i dont know what to do
check the recalls there is something in there about tail light and signals
If you replaced the flasher on your 1999 Mercury Cougar and your turn signals are still not working, you should check the turn signal fuse. This fuse is located under the dashboard on the driver's side of the vehicle to the left of the steering column.
It has one flasher that controls both the turn signals and the emergency flashers. If the turn signals are working then the flasher is not your problem. However the flasher relay is located on the drivers side, under the dash, above the fuse block, mounted on the kick panel.
Did you happen to check the turn signal flasher before you installed the switch?
Defective flasher module - common problem
You di dnot mention the kind of car. Most cars have a turn signal flasher and an emergency flasher.Are you sure that you replaced the right one?