If you turn on your 1999 mustang v6 car and the right signal light stays on and doesn't blink and you switch the car off and then the left signal light stays on without blinking, then you need to see a mechanic.
More then likely it needs to be replaced, if its the actual signal inside the car, turn it on check outside the car which one it is and replace!!
If the lights blink fast on either side of the car then this means you either have non-factory bulbs in the car or you need to replace your blinkers because one of your lights is out.
your rear bulb is blown - replace the bulb The turn signal blinks fast because the bulb is going out. That is also why the others dont blink.
try replacing the blinker under the dash that little box that makes the blinker sound
turn signal relay is bad
Buy a "highway" turn signal flasher
Hitch the trailer. Connect the lights. Start your car or truck. Turn the turn signal on. Get out and go behind the trailer. See if they blink. Repeat for the other side.
Why would you want the blinker faster. They should blink at factory specs.
The turn signal switch is directly under the steering wheel. the flasher...(the device that makes the lights blink and is activated by the turn signal switch) is usually under the steering column between the column and pannel
Check your bulbs and your flasher.
It typically means you have a bulb on that side not working. Can't remember if it's front or back. It doesn't matter what end of the car the burned out bulb is on. Just compare the good side blinkers with the bad side blinkers. what ever bulb or bulbs are bruned out will be fairly obvious, it also help to do this check in the shade, makes it easier to spot the burned out bulb.