Electric forklift EP20KT.
Operator was lifting and the error code 33 came up. He turned it off then on and tried to move but code 13 displayed. Reset again and moved about 10 feet before error codes 11 and 21 displayed. I shut the lift off and turn it back on with no errors indicated, I attempt an action and sometimes it will work momentarily but I soon get the alarms 30 or 33 when using the hydraulics, otherwise I get 13 or 11 and 21 when I attempt to move.
What ever is wrong it will intermittently allow the lift to work, it effects the hydraulic system and the drive system. The battery voltage remains above 36v. The diodes test good, the capacitors test good, the thyristors are not shorted. Any suggestions?