Engine Does Not Start - Komatsu PC130-7 Shop Manual

TROUBLESHOOTING
E-1 Engine does not start
Trouble

• Engine does not start

Related
• The engine starting circuit is equipped with the start lock function of safety lock lever type.
information
1 Low charge level of battery
2 Defective fuse No. 3 or 18
Defective starting switch
3
(Internal disconnection)
Defective safety lock switch
4
(Internal disconnection)
Defective starting motor
cutout relay R11 or R13
5
(Internal disconnection or
short circuit)
Possible causes
and standard
value in normal
state
Defective starting motor
6 safety relay
(Internal defect)
Defective starting motor
7
(Internal defect)
20-404
(1)
Cause Standard value in normal state/Remarks on troubleshooting
If the fuse is broken, the circuit probably has a grounding fault, etc.
(See Cause 10.)
If the fuse is not broken and the monitor panel does not light up, check
the power supply circuit between the battery and fuse box, too.
aPrepare with starting switch OFF, then carry out troubleshooting with-
out turning starting switch.
H15 (male)
Between (1) and (4)
aPrepare with starting switch OFF, then carry out troubleshooting with-
out turning starting switch.
S14 (female)
Between (1) and (3)
aPrepare with starting switch OFF, then carry out troubleshooting with-
out turning starting switch.
aPrepare with starting switch OFF (Disconnect only terminal C), then
turn starting switch to START position and carry out troubleshooting.
Between B and
chassis ground
Between E and
chassis ground
Between A27 (2) and
chassis ground
Between A27 (1) and
chassis ground
Between C and
chassis ground
If the power supply, GND, generation signal, and starting input are nor-
mal and the starting output is not normal, the starting motor safety relay
is defective.
aPrepare with starting switch OFF, then turn starting switch to START
position and carry out troubleshooting.
Between B and
chassis ground
Between C and
chassis ground
If the power supply and starting signal are normal and the starting motor
does not rotate, the starting motor is defective.
Battery voltage
Min. 24 V
Starting switch
OFF
START
Safety lock lever
Free
Lock
R11 (female), R12
Between (1) and (2)
Between (3) and (5)
Between (3) and (6)
Relay terminal, A27
Power
supply
GND
Genera-
tion signal
Starting
input
Starting
output
Starting motor
Power
supply
Starting
output
Electrolyte specific gravity
Min. 1.26
Resistance
Min. 1 Mz
Max. 1 z
Resistance
Min. 1 Mz
Max. 1 z
Resistance
100 – 500 z
Min. 1 Mz
Max. 1 z
Starting
Voltage/Resistance
switch
20 – 30 V
Max. 1 z
START Max. 1 V
20 – 30 V
20 – 30 V
Starting
Voltage
switch
20 – 30 V
START
20 – 30 V
PC130-7
E-1