Komatsu 4D98 Series Shop Manual page 149

10.1.3 Troubleshootincl
Turn key switch to ON.
Does the charge lamp
come ON?
Disconnect GN coupler
Ground L-terminal of the
driven machine side coupler
(L, tG).
OFF
Replace the charge lamp
Does the charge lamp
come ON?
The charge lamp is available from
I
the driven machine manufacturer.
Turn the key switch to START.
(The engine starts.)
ON
Inspect the rotor coil and
brush IC-RG
Inspect or replace the fan belt,
and inspect the alternator
tnspect the diode (0 side)
increase the engine speed to
1500 rpm and turn the fight
switch to ON.
The lamp is lit
dimly.
Measure VB and VL at
BAT L-terminal during
idling
I /
I I
Excessive voltage drop between
BAT and batt
(@
side) terminal.
OFF
L-terminal defective conduction.
* Inspect the diode (8 side).
Measure VB at BAT terminal
with the engine running at
1500 rpm
VB > 15.5
J
, 1 I \
Turn the light switch
t----4
Does the charge lamp
to ON during idling come ON?
Inspect the auxiliary diode
Not abnormal
3) The check method is also applicable to