a serial number of truck would be most helpful

but assuming this truck has microcommand control the error code 30 indicates a shorted T1P or T2P transistor.
possible causes are:
- open wiring
- failed pump driver board
- failed logics
- open circuit in pump motor PA1
- PS2 cables
- welded pump contactor tips

check all connections related to the pump circuit
check the pump contactor tips, make sure they are not welded shut
check the pump motor & cables for shorts

if all of the above check ok then there is a possibility the pump driver board is bad.
in any case the smoking transistor should be replaced and the cause of the problem found that caused the transistor to release it's magic smoke :o)