Komatsu 4D98 Series Shop Manual page 156

IO. Alternator
@ Measure voltage at V2 (voltage
across terminals F and E) while
gradually increasing the resistance
of the variable resistor starting from
0 V. Check that there is a point
where the V2 voltage reaches 2.0 V
or less of the Vl value of BAT1
measured in @ above. If no
change occurs, the regulator is
faulty. So, replace it with a new
one.
@ Measure voltage at V4 (voltage
across the intermediate tap of the
variable resistor and E-terminal),
with variable resistor Rv being
fixed. If the measured value is
within the specified range, the
regulator is acceptable. If not, the
regulator is faulty. So, replace it
with a new one.
10-10