How did you check the code? Maybe a fuse blew when you checked it.

I believe code 54 has to do with either.

-Crankshaft Speed Fluctuation Sensor *Intermittent Interruption*

-Crankshaft Speed Fluctuation Sensor *No Signal*
(someone who knows more will correct me if I'm wrong)

I have no idea how to troubleshoot this code. Maybe you need to just replace a sensor.