E-2. Preheater Does Not Operate Normally - Komatsu WA250-6 Shop Manual

SEN03848-00

E-2. Preheater does not operate normally

a) Preheater does not operate
Contents of
• When temperature is low (engine boost air temperature is below –4°C), preheater does not operate.
trouble
• If failure codes are displayed, carry out troubleshooting for them first.
Related
• Engine boost air temperature can be checked with monitoring function.
information
(Monitoring code: ENG-18500-CHG TEMP (°C))
(Monitoring code: ENG-18501-CHG TEMP (V))
Defective heater relay
1
(Internal defect)
Defective intake air heater
2
(Internal defect)
Possible
causes and
Defective diode (E06A)
standard value
3
(Internal defect)
in normal state
Disconnection in wiring har-
ness (Disconnection in wiring
4
or defective contact in connec-
tor)
Ground fault in wiring harness
5
(Contact with GND circuit)
10
40-400
Causes
a Turn starting switch OFF and remove heater relay.
a Check heater relay unit.
Between E05 – E07A
a Prepare with starting switch OFF, then carry out troubleshooting
without turning starting switch ON.
Between E07B – ground
a Prepare with starting switch OFF.
a Replace diode (E06A).
Condition becomes normal.
Condition does not become nor-
mal.
a Prepare with starting switch OFF, then carry out troubleshooting
without turning starting switch ON.
a Measure in diode range.
Between (2) – (1)
a Apply (+) side of tester to (2).
a Prepare with starting switch OFF, then carry out troubleshooting
without turning starting switch ON.
Wiring harness between E07A – E07B
Wiring harness between R11 – E05
a Prepare with starting switch OFF, then carry out troubleshooting
without turning starting switch ON.
Between wiring harness E07A – E07B and
ground
Between wiring harness R11 – E05 and
ground
400 Troubleshooting of electrical system (E-mode)
E-2. Preheater does not operate normally
Standard value in normal state/Remarks on troubleshooting
Heater relay E06 – R90
When 24 V is applied
(When relay is "ON")
Other than above
(When relay is "OFF")
Between E06 – R90
Resistance
Max. 1 z
Min. 1 Mz
19 – 25 z
Resis-
tance 0.27 z
Diode (E06A) is defective.
Diode (E06A) is normal.
Continuity is secured.
Resis-
Max. 1 z
tance
Resis-
Max. 1 z
tance
Resis-
Min. 1 Mz
tance
Resis-
Min. 1 Mz
tance
WA250, 250PZ-6
1
0.17 –