Rear right red light not working, works only during braking . Changed the bulb, nothing . What's wrong

[adigr]

Rear right red light not working, works only during braking . Changed the bulb, nothing . What's wrong

 

[novocaine]

brake filament is a separate live but a shared earth so earth fault is ruled out at least.

bulb has 2 filaments, you should be able to see if one is broken. check the old and the new bulb (check the simple stuff first).
then clean the contacts in the bulb holder (next simplist to check).
if that doesn't work you'll need a multimeter as it's potentially a break in the wire, but I suspect the above will sort it.

 

[adigr]

brake filament is a separate live but a shared earth so earth fault is ruled out at least.

bulb has 2 filaments, you should be able to see if one is broken. check the old and the new bulb (check the simple stuff first).
then clean the contacts in the bulb holder (next simplist to check).
if that doesn't work you'll need a multimeter as it's potentially a break in the wire, but I suspect the above will sort it.

Old Bulb filament is not broken, but I bought a new bulb anyways , i also cleaned the contacts. During night as car is moving only the left rear red light working , right one doesn't work, but when I brake it does work . Used multimeter too, not break in the wire. Still can't find the root of the problem