Back left turn signal light won't work. Front left turn signal light works fine. what to do?

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

was the correct bulb used? this sounds like a single function bulb was used NOT the bulb that will light with the headlights and ALso produce turn singles

Turn the left on. Look and see which light comes on, Front or back. The one that doesn't come on is the problem. You have an open wire/ broken. Could be power or ground. Usually the wire breaks close to the plug. Or the plug itself could be the problem. Look for black or missing tabs in the socket where the light bulb goes. These tabs also bend with heat/electricity. Use a paper clip and bend them back in.

have you checked the bulbs front and back. to see if they work, bulb check. then it sounds like you might have a bad signal flasher that only works the left side and not the right side. or if a bulb at the front or the rear gets bright but not the opposite bulb on the same side then you may just have a bad bulb or socket or power to the socket when doing the bulb check.

vehicle?????????

Gday mate, we had a problem with another late model vehicle similar to that, the bulb that was put into the reverse light was not exact brand product ( ohmage was slightly wrong ) and fowled up computer, correct bulb in place and disconnect battery to reset K A M ( keep alive memory) problem solved, BEWARE, some vehicles cannot have KAM reset except for dealer computer tethered reboot , just try putting the factory correct bulb(s) in and see how it goes, geoff. hope this helped.

No, because the left side is still working. The loose wiring was to the multifunction switch (turn signal).

Power gores through the turn signal switch to the brake switch on the brake pedal, then to the rear lights. Does the highmount brake lamp work?
At the RH lamp socket, Measure the voltage between the RH rear lamp C4032 pin 3, circuit 5 (OG/LB), harness side and ground. Should be 12 volts.

try that first.

Did you change the front and rear bulbs?

Check the new bulb make sure it is a 4157 bulb. If it is the correct bulb, try switching the left and right bulbs to see if the problem is still on the right side. Check the wiring on the right side, look for damaged or disconnected wiring.

Replace the turn signal switch. Bad contact inside causing a crossing of the circuits. When the turn signal is applied it should open the brake light circuit allowing for just the signal to work. Doesn't sound like the switch is doing it's job.

turn on the hazard light so you can identify the bulb that is actually deffective. the procedure to replace can be found on youtube.