Husqvarna Automower 420 Technical Manual page 85

Motors
20/21 Wheel motor blocked,
right/left
22/23 Wheel motor problem,
right/left
35/36 Wheel motor over-
loaded, right/left
25 Blade motor blocked
40/42/46 Limited cutting height
range
41 Unexpected cutting height adj
43 Cutting height problem, drive
44 Cutting height problem, curr
45 Cutting height problem, dir
46-47 Cutting height blocked
6. TROUBLESHOOTING
Grass or other object has
wrapped around the drive
wheel.
The wheel motor is faulty
The main circuit board is faulty Change main circuit board, refer to
The cabling to the wheel mo-
tor is damaged
Grass or other object has
wrapped around the drive
wheel.
Grass or another object may
have become wrapped around
the blade disc.
The blade disc is lying in a
pool of water.
The blade motor is defective.
The main circuit board is de-
fective.
The cabling to the blade motor
is damaged or faulty.
The cutting height adjustment
cannot move.
The cutting height adjustment
motor is incorrectly fitted or
faulty.
The cutting height sensor cir-
cuit board is incorrectly fitted
or faulty.
The cutting height adjustment
has been altered without a re-
quest from the mower
Check the drive wheel and remove
any objects.
Check the wheel motors' function
when idling.
5.8 Replacing the MCB on page 65.
Check whether the damage is re-
pairable. Otherwise replace the wheel
motor.
Check the drive wheel and remove
any objects.
Check the blade disc and remove any
object.
Move the mower and rectify the cause
of water collecting in the working area.
Make sure the blade motor has the
right speed, refer to 5.1.7 Cutting mo-
tor on page 58.
Change main circuit board, refer to
5.8 Replacing the MCB on page 65.
Check whether the damage is re-
pairable. Otherwise replace the blade
motor.
Check that the cutting height adjust-
ment can move by disassembling the
chassis. Check all moving parts in the
cutting height system.
Check that the motor cabling is fitted
correctly. Replace the motor if re-
quired.
Check that the cutting height sensor
circuit board is correctly fitted. Re-
place the board if required.
Carry out a cutting height calibration.
Refer to 2.6.6 Calibration on page 34.
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