99 Caravan 2.4L - service engine light with code 55??

99 Caravan 2.4L, 38K miles. Service engine light went on. Gas cap was loose, almost off completely, so I tightened it. I checked the codes by 1) holding Reset and Trip buttons on odometer, 2) key to ACC, 3) release buttons after 5 seconds, 4) push Trip button. Odometer flashes only 55. Is the 99 Caravan 2.4L an old style code, i.e. 55 means "end of codes"? But the Service Engine light is still on. Is there a fuse I can pull to reset the PCM and clear the code? I don't have the skill or guts to disconnect the battery myself.

Thanks much. -R.