2009 V50 back up lights are both out. What could it be? Not the fuse or bulb.

SOURCE: 1991 volvo tail lights

Could you take out a bulb and with a testlight/probe check that you do in fact have power to that circuit .Also check that they are the correct bulb for that application I have seen people put indicator bulbs in where therse supposed to be a double filament bulb.Does the base of the bulbs lead contacts line up with the two steel terminals inside the plug?

SOURCE: mazda 6 reverse lights

ITS POSSIBLE THAT YOUR REVERSE LIGHT SWITCH IS FAULTY BEST WAY TO FIND OUT IS TO DISCONNECT REVERSE SWITCH AT G/BOX & BRIDGE OUT CONNECTIONS WITH IGN ON & IN REVERSE LIGHTS SHOULD GO ON IF THEY DO THEN ITS YOUR SWITCH.

SOURCE: Left rear brake light stopped working but bulb and fuses are OK.

take the bulb back out have someone sit in car apply brake get your self a circuit tester and check to see if this circuit is carrying efficient 12 volt current! some times in cold weather these bulbs get hot with long period of breaking and when released condensate and rust begins and you get what you have perhaps bad socket! this would be a ideal location to begin and probably end,

SOURCE: renault clio 1.2 16v dyn REAR LIGHTS NOT WORKING

So thankful for this site and the answer to the problem, which was infact the black connectors under the passenger side well..Cheers again i've saved myself £100's x

SOURCE: 2005 Toyota Sienna rear brake light problem.

have you checked the earthing continuity-if it's this other bulbs may also partly light when brakes used
otherwise-
Check continuity of live from center to lh & rh lights and/or is there a live at those lights