1523.6-0000010 OM
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6.3 Possible failures in the electronic control system for rear axle differential lock,
front driving axle drive, front power take off shaft, GB reduction gear and instruc-
tions for their troubleshooting
The list of possible failures in the electronic system for rear axle DL, FDA drive, FPTO (if
mounted), GB reduction gear (if mounted) and instructions for their troubleshooting are
shown in Table 6.3.1.
Table 6.3.1
Failure,
external manifestation, cause
Troubleshooting
FDA drive or rear axle DL can not be engaged in the forced mode, or GB reduction
unit can not be shifted to the higher pass, FPTO drive can not be engaged
Power supply voltage is not trans-
ferred to the respective distribution
valve solenoid
Check according to the electric circuit diagram if
the power supply voltage is transferred to the re-
spective distribution valve solenoid
Jamming of the respective distribu-
tion valve spool
Rinse the distribution valve
None of the drives (FDA, rear axle DL, FPTO) can be engaged and GB reduction
unit can not be shifted to the high gear
There is no pressure in the trans-
mission hydraulic system
Eliminate the failure in the transmission hydraulic
system
When the front PTO drive is engaged, indicating lamp lights up but the PTO shaft
end extension fails to rotate
Make sure that the cylinder pin is
moving while engagement
If the cylinder rod is moving, FPTO shaft electric
control is operating in a proper manner
Rear axle DL can not be engaged in an automated mode when guide wheels are in
the forward motion position
Electric circuit breakage to drive
wheels rotation angle sensor
Check electric circuits according to the electric
connections diagram
Drive wheels rotation angle sensor
is not adjusted properly
Adjust the sensor – the operating clearance be-
tween the sensor butt end of drive wheels rotation
angle sensor 7 (figure 6.3.1) and the overhang on
center pin axis 9 butt end shall be adjusted by
means of the required number of gaskets 8 so that
while axis turning in relation to the middle position
to both sides for the angle (13±2)°, sensor 7 acti-
vates. The increased number of gaskets leads to
the reduction of sensor operating angle, the de-
creased number of gaskets leads to the increase of
sensor operating angle
While tractor slowing down (depressing both brake pedals simultaneously), FDA
drive can not be engaged and rear axle DL can not be disengaged (depressing ei-
ther of the brake pedals)
Faulty one or both brake actuation
sensors
ВК
12-21 (actuation of
brake pedals)
Simulate sensor actuation one-by-one by means of
contact closure in cable sockets to the sensors.
Replace the faulty sensor
Cable of connection to sensors
ВК
12-21 is faulty
Check the cable for operability according to the
electric circuit diagram
Faulty relay in FDA drive actuation
circuit and rear axle DL deactiva-
tion circuit while slowing down
Replace the relay