Failure Code [Dw7Bky] Fan Reverse Solenoid Circuit: Hot Short - Komatsu WA250-6 Shop Manual

SEN03846-00

Failure code [DW7BKY] Fan reverse solenoid circuit: Hot short

Action code Failure code
E01 DW7BKY
Contents of
• Abnormal voltage was generated because of hot short in fan reverse solenoid relay output system
trouble
when fan reverse solenoid relay output was turned ON.
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.
Problem that
appears on
• Fan does not reverse (Manual reverse function and automatic reverse function do not work).
machine
• 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: Start engine, wait for at least 30 seconds, and then press man-
ual reverse switch.
Defective fan reverse sole-
1
noid relay (Internal defect)
Possible causes
and standard
value in normal
state
Hot short (Contact with 24V
2
circuit) in wiring harness
3 Defective HST controller
34
40-360
Fan reverse solenoid circuit: Hot short
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.
Wiring harness between HST
(female) (37) – L104 (female) (2)
a Prepare with starting switch OFF, then start engine and carry out
troubleshooting.
360 Troubleshooting by failure code (Display of code), Part 6
Failure code [DW7BKY] Fan reverse solenoid circuit: Hot short
Standard value in normal state/Remarks on troubleshooting
Condition becomes
normal
Condition does not
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
Voltage (In fan for-
20 – 30 V
ward mode)
Voltage (In fan
Max. 1 V
reverse mode)
Voltage
20 – 30 V
Max. 1 V
WA250, 250PZ-6
200 –
400 z