Doosan B20S-3, Specifications Systems Operation Testing & Adjusting, Page: 86 / 123

85 MicroController Control System Troubleshooting
PROBLEM 30
Display = “F2”, no lift truck operation.
POSSIBLE CAUSE
Opened the motor cable (A1, A2, S1, S2).
Opened the armature coil or field coil in drive motor.
Contactor failure. Shorted MOSFET TD in Drive Module.
CHECKS
Check conditions under which faults is detected.
At the keyon
As soon as the accelerator pedal
is completely released for doing
Running with
contactors on running
positions
See point G). See point F).
See point F).
Disconnect the motor cable
connected to the battery and
then verity if the alarm
still present
Yes No
See point C), D), E).
A running contactor is
locked in working position
Yes No
See point A). See point B).
The stuck contactor
coil is supplied?
Yes No
Points
A) If the running contactor remains stuck, you can verify :
1) if the wire going from FWD contactor coil to REV contactor coil is casually in short with a metallic part connected to the
battery negative :
2) disconnecting the contactor wire always exited from board connactor if the contactor is no longer exited, replace the logic
board.
B) A running contactor is stuck on working position, unlock the contact, it could be possible to replace the contactor.
C) Wrong connections of the motor cables. The field and the armature are crossed.
D) There is a current dispersion on the motor between the field winding and the armature one otherwise there are some electric
parts of these windings that makes a contact inside the motor.
E) Check that there are not metallic parts inside the contactor board that cause a short towards the negative in the points
connected to SH- and SH+.
F) The most probably reason is that the failure is inside the controller, replace it.
G) If there’s the bypass contactor check that it is not stuck or it is too much slow in opening. For verifying this possibility, disconnect the
bypass and check if the failure disappears : if this happens, replace the logic.