CRANKSHAFT AS 4685121 - Caterpillar

Illustration 1 g00867614
Field winding (1) Rear frame (2) Leads for the field winding (3) Field windingThe illustrations below show The N3 series alternator (35 amperes).Field Winding Continuity Test
Illustration 2 g00867623
Field winding continuity test (2) Leads for the field winding (4) Lead for the rectifier
Remove the rear cover.
If the alternator has a capacitor, remove the capacitor.
Remove the regulator.
Connect the multimeter leads across field winding leads (2). This is shown in Illustration 2.
Measure the resistance between the field winding leads.Expected Results: N3 Series Alternators (50 amperes) ... 8 1 ohms N3 Series Alternators (35 amperes) ... 12.9 .65 ohmsResults:OK - The resistance is within tolerance. The field winding is normal. STOP.NOT OK - The resistance is above tolerance. The field winding has an open circuit. Replace the field winding. STOP.NOT OK - The resistance is below tolerance. The field winding has a short circuit. Replace the field winding. STOP.Field Winding Ground Test
Illustration 3 g00867625
Field winding to ground test (2) Leads for the field winding (4) Lead for the rectifier (5) "B-" terminal
The rear cover, the capacitor, and the regulator remain removed from the alternator.
Connect one multimeter lead to the "B-" terminal. Connect the other multimeter lead to one of the field winding leads (4). This is shown in Illustration 3.
Measure the resistance.Expected Result: The resistance is greater than 100000 ohms.Results:OK - The resistance is greater than 100000 ohms. Repeat steps 1 to 3 for the other field winding lead (2). If all of the results are OK, the stator is normal. STOP.NOT OK - The resistance is NOT greater than 100000 ohms. The field winding lead is shorted to the frame. Replace the field winding. STOP.