Rick,

Sounds like you are looking at the A/C connection for the charger. If the charger loses connection to this plug or the battery is below charger minimum, the lights will flash. Check your battery voltage first. Should not be below 24 volts. Fully charged voltage should read 26.5 to 27.5 volts depending on age. Should batteries read below 21 volts, may need to use a portable charger to raise voltage high enough for charger to read. Good Luck.