code 33 is actually a mix of 2 other problems
also the service manual is kinda strange in this one because of the way they list the problem codes v/s the display codes, it can be confusing.
Anyway the manual lists it as problem #24 Display '33'

display shows 33, action light ! illuminates, no lift truck operation: line contactor closes and opens.

possible causes: failure in pump circuit

in the checks it refers to problem 22 and 23 (display '31' and '32')

so we go to problems 22 and 23.

possible causes listed for problem 22 (display31) code are:
Faulty wire connections: D4P, or T1P and T2P failed, failed pump driver board or failed logics.

possible causes listed for problem 23 (display 32) code are:
Faulty wire connections: D4P, or T1P and T2P failed, failed pump driver board or failed logics.

both have same possible causes.

- look for ANY burned connectors, connections or wires
- loose connections
- smashed or compressed connectors, corrosion or foreign material
- Also check:
Wire #45 from emitter of transistor T1P and T2P to P4-7 and P2-10
Wire #34 from pump driver board to pos heatsink
Wire #1 from pump driver board to neg heatsink
Wire #119 from pump shunt (+) to P2-18
Wire #29 from pump shunt (-) to P2-19

repair any defects and reconnect wires

of course you want to test diodes:
D4P
check transistors:
T1P and T2P
check pump driver board
check head capacitor also

replace any that fail checks

if all components pass tests the replace logics