Komatsu 830E Shop Manual page 140

Coil Test
1. Using an ohmmeter, measure the coil resis-
tance across the coil terminals.
a. The coil should read approximately 28Ω at
72°F (22.2° C).
b. If the ohmmeter reads
and the switch must be replaced.
c. If the ohmmeter reads 0 Ω, the coil is shorted
and the switch must be replaced.
2. Place one of the ohmmeter probes on a coil ter-
minal and another on the switch mounting
bracket. If the meter displays any resistance
reading, the coil is grounded and the switch
must be replaced.
3. The ohmmeter should display when the probes
are placed across the switch terminals.
NOTE: The switch terminals should show continuity
when 24 VDC is applied to the coil terminals,
however high resistance across the internal switch
contacts due to arcing etc. could prevent the switch
from delivering adequate current to the cranking
motor. If the coil tests are satisfactory but the switch
is still suspect, it should be replaced with a new part.
D2-22
∞
, the coil is open
24 VDC Electric Supply System D02023