Failure Code [Dw7Bkz] Fan Reverse Solenoid Circuit: Disconnection/Ground Fault - Komatsu WA250-6 Shop Manual

SEN03846-00
Failure code [DW7BKZ] Fan reverse solenoid circuit: Disconnection/
Ground fault
Action code Failure code
E01 DW7BKZ
Contents of
• Fan reverse solenoid relay cannot be controlled because of disconnection or ground fault in fan
trouble
reverse solenoid relay output system.
Action of • Keeps output to fan reverse solenoid turned OFF and stops fan reverse control function.
controller
• Even if trouble disappears, system does not reset itself until starting switch is turned OFF.
• Manual reverse function and automatic reverse function do not work.
Problem that
appears on
• Fan always turns forward (When there is disconnection).
machine
• Fan always turns in reverse (When there is ground fault).
• Output state (ON/OFF) to fan reverse solenoid relay can be checked with monitoring function.
Related
(Monitoring code: HST – 40980 – D-OUT-17)
information
• Method of reproducing failure code: Turn starting switch ON.
Defective fan reverse sole-
1
noid relay (Internal defect)
Defective VIS power supply
2 holding relay (Internal short
circuit)
Possible causes
and standard
value in normal
state
Disconnection in wiring har-
ness (Disconnection in wiring
3
or defective contact in con-
nector)
Ground fault in wiring har-
4 ness (Contact with GND cir-
cuit)
5 Defective HST controller
36
40-360

Failure code [DW7BKZ] Fan reverse solenoid circuit: Disconnection/Ground fault

Fan reverse solenoid circuit: Disconnection/Ground fault
Trouble
(HST controller system)
Causes
a Prepare with starting switch OFF, then turn starting switch ON
and carry out troubleshooting.
Replace fan reverse
solenoid relay (L104)
with another relay.
a Prepare with starting switch OFF, then carry out troubleshooting
without turning starting switch ON.
Between L104 (male) (1) – (2)
a Prepare with starting switch OFF, then start engine and carry out
troubleshooting.
Replace VIS power
supply holding relay
(L102) with another
a Prepare with starting switch OFF, then carry out troubleshooting
without turning starting switch ON.
Between L102 (male) (1) – (2)
a Prepare with starting switch OFF, then carry out troubleshooting
without turning starting switch ON.
Wiring harness between HST (female) (37) –
L104 (female) (2)
Wiring harness between L104 (female) (1) –
L102 (female) (3)
a Prepare with starting switch OFF, then carry out troubleshooting
without turning starting switch ON.
Between wiring harness HST (female) (37) –
L104 (female) (2) and ground
a Prepare with starting switch OFF, then start engine and carry out
troubleshooting.
360 Troubleshooting by failure code (Display of code), Part 6
Standard value in normal state/Remarks on troubleshooting
Condition becomes
normal
Condition does not
become normal
Condition becomes
Condition does not
relay.
become normal.
HST Fan condition
In fan forward mode
Between (37) –
ground
In fan reverse mode
Relay (L104) is
defective
Relay (L104) is
normal
Resis-
tance
Relay (L102) is
normal. defective.
Relay (L102) is
normal.
Resis-
tance
Resis-
tance
Resis-
tance
Resis-
tance
Voltage
20 – 30 V
Max. 1 V
WA250, 250PZ-6
200 –
400 z
200 –
400 z
Max. 1 z
Max. 1 z
Min. 1 Mz