The two tail/stop light bulbs are wired in parallel, not series. If one goes out the the other should still work.
Originally Posted by roadstar
As to your original question, there are no fuses on the RT. The central electronics unit (also known as the ZFE) monitors the current on each circuit, and shuts down a circuit that draws too much current, as in a short circuit condition. Once the fault is corrected, the circuit will automatically reset after turning the ignition off, then back on. If a circuit draws too little current the ZFE will generate an error code and in some cases activate a warning light, as you have seen with your tail lamps.