Magnetic Switch Continuity Test - Komatsu 4D98 Series Shop Manual

9. Starting Motor
W
c)
(4)
Check of brush movement
If the brush does not move smoothly, inspect the brush holder for bending and the brush
holder sliding surface for dirt. Repair or clean as needed.
Check the continuity between the insulated brush holder (positive (+)) and the brush holder
base (negative (-)).
If they are electrically continuous, replace since the holder is grounded.
(Checking insulation of brush holder)
Magnetic switch continuity test
Continuity test
Measurement point
Normal
Abnormal (cause)
Shunt coil
Between C and ground
Yes
None (open circuit)
Series coil
CandM
None
Yes (short-circuiting)
Replace if needed.
(Magnetic switch connection diagram)
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