What was found
DEN - FLT 7407 - EN ROUTE FROM DEN TO DRO, THE FLIGHT CREW REPORTED THE 'EMERGENCY/PARKING BRAKE ACCUMULATOR' LOW PRESSURE ANNUNCIATION LIGHT ILLUMINATED IN-FLIGHT. CREW PERFORMED CHECK LIST ITEM IAW FLIGHT STANDARDS MANUAL, HOWEVER, LIGHT ILLUMINATED ONCE AGAIN A SHORT TIME LATER. CREW ELECTED TO RETURN TO DENVER. AIRCRAFT LANDED IN DENVER WITHOUT FURTHER INCIDENTS. DENVER MAINTENANCE CLEANED CANNON PLUG CONNECTOR ON THE PRESSURE SWITCH. UNABLE TO DUPLICATE DISCREPANCY. AIRCRAFT RETURNED TO SERVICE. (X)