Preheater Does Not Operate - Komatsu PC130-7 Shop Manual

TROUBLESHOOTING
E-7 Preheater does not operate
Trouble (1) When the starting switch is set in the HEAT position, the preheating monitor does not light up.
• The preheater monitor lights up when the starting switch is turned to the HEAT position and starts flash-
ing about 30 seconds after to notify the operator of completion of preheating (It stops flashing about 10
Related
seconds after).
information
• The input state (ON/OFF) of the preheating signal can be checked with the monitoring function.
(Code: 045, Center of upper line)
1 Defective starting switch
Disconnection in wiring
harness
Possible causes
2 (Disconnection in wiring
and standard
harness or defective
value in normal
contact in connector)
state
3 Defective monitor panel
Trouble (2) When the starting switch is turned to the HEAT position, the heater unit does not become hot.
Related • If the engine is started while the temperature is low (the coolant temperature is below 30°C), the gov-
information ernor and pump controller drives the heater relay automatically to preheat the engine.
1 Defective starting switch
Defective heater relay
2
(Internal disconnection)
Possible causes
and standard
value in normal
state
Defective electrical intake
3 air heater
(Internal disconnection)
Disconnection in wiring
harness
4 (Disconnection in wiring
harness or defective
contact in connector)
20-416
(1)
Cause Standard value in normal state/Remarks on troubleshooting
If the engine is not preheated (the heater unit does not become hot),
carry out troubleshooting for trouble (2).
aPrepare with starting switch OFF, then carry out troubleshooting with-
out turning starting switch.
Wiring harness between P02 (female) (18) and
J02 (male) (7)
aPrepare with starting switch OFF.
Between (17) and
chassis ground
Cause Standard value in normal state/Remarks on troubleshooting
aPrepare with starting switch OFF.
H15 (male)
Between (1) and (3)
aPrepare with starting switch OFF.
Heater relay
Between A25 and
chassis ground
Between contact
aPrepare with starting switch OFF, then carry out troubleshooting with-
out turning starting switch.
Electrical intake air heater
Between E01 and chassis ground
aPrepare with starting switch OFF, then carry out troubleshooting with-
out turning starting switch.
Wiring harness between H15 (female) (3) and
J02 and A25
Wiring harness between A22 and heater relay
Wiring harness between A26 and E01
P02 Starting switch
HEAT
Starting switch
HEAT
Starting switch
HEAT
terminals
Resistance
Voltage
OFF Max. 1 V
20 – 30 V
Resistance
OFF Min. 1 Mz
Max. 1 z
Continuity/Resistance
OFF There is continuity
Max. 1 z
Continuity
There is continuity
Resistance
Resistance
Resistance
E-7
Max. 1 z
Max. 1 z
Max. 1 z
Max. 1 z
PC130-7