right rear turn-signal light goes on but doesn%27t flash

90% of the time when you get a solid turn-signal on only one-side of the vehicle, or a rapid blink, you've got a burnt-out turn signal bulb. Check all of the bulbs, you may have a front blinker or corner marker that's burned out. If both sides were doing it I would say it probably needs a relay but since it's isolated to one side, start with the bulbs. Also make sure that it has the RIGHT bulbs installed....there are lots of part numbers for bulbs and often there will be 2 or 3 part numbers that look nearly identical.