All signals and other flashers work but passenger front flashers do not work

How do I know if my flasher relay is bad?

Symptom of a bad or failing turn signal / hazard flasher is hazards or turn signal lights that do not function. If the flasher breaks or has any internal issues it can cause the lights to malfunction, or not respond at all when the turn signal lever or hazard light button are pressed.
Jan 19, 2016

Symptoms of a Bad or Failing Hazard / Turn Signal Flasher - YourMechanic

For the cost involved, I would change it.

https://www.fixya.com/cars/t24552531-flasher_turn_signal_located

https://www.google.com/search?q=2011+kia+sorento+flasher+relay

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The side that is dim has resistance in the electrical circuit , use voltage drop testing to find the problem . Watch this video on voltage drop testing .

https://www.youtube.com/watch?v=YaYtCVBodpw&t=1s

The flasher is under the dash.If you turn on the signal listen for it's location.Turn on your 4 way flasher and see if the left rear light is flashing.If it's not then replace the bulb.If it still does'nt work after replacing the bulb check if there is power to the socket. Use a probe light.If no power to the socket.There is a break in the wire or worse the signal switch may be the culprit

Dear Alex,
The problem is in the bulb, or the socket, or the wiring to these.
Whenever a turn signal flashes fast, know that one of the bulbs is not working.
You have already identified the problem as being the front one. Problem could be the hot wire, or the ground wire, or the ground connection to this bulb.
Start by taking a tester to the hot wire, and see if it is receiving electrical impulses when the turn signal is on.
( It probably is, unless the car has been in a wreck and has been improperly repaired.)
Then check the socket or the wires to is and see if the bulb is grounded.
I suspect the ground is defective, and either a new socket or a repair to the ground wire should fix you rights up.
God bless your efforts.

try changing the signal flasher. note the e-flasher looks the same. when you find a flasher turn on the e-flasher so you know you have found the signal flasher. they are usually in the same general area.

Check you bulbs first because a bad bulb will cause this also !

Do they work when you turn on the 4-way hazard flasher? If so, look at the BCM (body control module) located under the passenger kick panel.

This may have more then one bulb in the front or possibly a bad socket try wiggling the new bulb in the socket to see if it will work.Compare all turn signal lights that come on the passenger side to those drivers side.Some vehicles also incorporate sidemarker lights with the turn signals.

Check for head light (daytime)relay to be bad,this might have to do with the turn signals also,if the turn signals on this car,also have running lights in them,If this relay is not bad,replace the body control module.

If the fuses are good and the front and rear bulbs are good, change the flasher for the turn signals, even tho the right is working. If that doesn't fix the problem, it might be in the turn sgnal switch on the steering column.
If both bulbs are good for the backup lights and fuses are good, then the backup light switch, which is screwed into the side of the transmission has to bad.