Preheater Does Not Operate - Komatsu ecot3 PC300LC-8 Shop Manual

SEN02632-02
E-4 Preheater does not operate
Trouble (1) When starting switch is turned to HEAT position, preheating monitor does not light up.
• Preheater monitor lights up when starting switch is turned to HEAT and starts flashing about 30 sec-
onds after to notify completion of preheating (It stops flashing about 10 seconds after).
Related infor- • If engine coolant temperature is below 30°C, automatic warm-up system operates and preheating
mation monitor lights up for up to 30 seconds.
• Condition of starting switch (preheating) signal can be checked with the monitoring function.
(Code: 04500 Monitor input 1)
Defective starting switch sys-
1
tem
Disconnection in wiring har-
ness
Possible causes
2 (Disconnection in wiring or
and standard
defective contact in connec-
value in normal
tor)
state
3 Defective machine monitor
Trouble (2) • When starting switch is turned to HEAT position, preheater does not warm up.
Related infor- • During low temperature (coolant temperature below 30°C), pump controller drives the heater relay
mation for 100 sec. after engine start to automatically preheat.
Defective starting switch
1
(Internal disconnection)
Defective heater relay
2
(Internal disconnection)
Possible causes
and standard
value in normal
state
Defective intake air heater
3
(Internal disconnection).
Disconnection in wiring har-
ness
4 (Disconnection in wiring or
defective contact in connec-
tor)
14
Cause Standard value in normal state/Remarks on troubleshooting
If preheating fails to operate (the heater does not warm up), refer to
Trouble (2)
a
Wiring harness between P02 (female) (18) –
J02 (male) (7)
a
Between (16) –
chassis ground
Cause Standard value in normal state/Remarks on troubleshooting
a
Between (1) – (3)
a
Coil terminal – chassis ground
Between contact terminals
a
Between heater terminals
a
Wiring harness between H15 (female) (3) –
J02 – Heater relay terminal R17
Wiring harness between battery relay termi-
nal M (R03) – Heater relay terminal R15
Prepare with starting switch OFF, then carry out troubleshoot-
ing without turning starting switch ON.
Prepare with starting switch OFF
CM01 Starting switch
Prepare with starting switch OFF
H15 (male) Starting switch
Prepare with starting switch OFF, then carry out troubleshoot-
ing without turning starting switch ON.
Heater relay
Prepare with starting switch OFF, then carry out troubleshoot-
ing without turning starting switch ON.
Prepare with starting switch OFF, then carry out troubleshoot-
ing without turning starting switch ON.
40 Troubleshooting
Resis-
tance
Voltage
OFF Max. 1 V
HEAT 20 – 30 V
Resistance
OFF Min. 1 Mz
Max. 1 z
HEAT
Resistance
Min. 1 Mz
Normal if conductive
Resis-
tance
Resis-
tance
PC300, 350-8
1
Max. 1 z
Max. 1 z
Max. 1 z