BUMPER 1387125 - Caterpillar

Capacitor Test
Capacitor
(1) Housing. (2) Ring terminal.1. Remove the capacitor from the alternator.2. Place and hold ring terminal (2) on housing (1). This discharges the capacitor. Each time this test is done, discharge the capacitor.3. Put the multimeter on the 20M resistance (Ohms) scale. Connect a multimeter lead to ring terminal (2). Connect the other multimeter lead to housing (1).4. When correctly operating, the resistance is very low for a short period of time and then it should stabilize above 100 000 ohms (meter reading 0.10 or greater).5. If the reading is not correct, replace the capacitor.Field Coil Tests
Field Coil
(1) Leads. (2) Housing.Field Coil Continuity Test
1. Put the multimeter on the 200 ohm resistance (Ohms) scale. Touch and hold a meter lead on each lead (1).2. For correct operation, the resistance value is: 3T6352 ... 6.3 to 7.3Ohms5N5692 ... 8.5 to 9.5Ohms7G7889 ... 1.7 to 2.1Ohms3. If the resistance is not correct, the field coil is open or shorted. Replace the field coil.Field Coil Ground Test
1. Put the multimeter on the 20M resistance (Ohms) scale. Touch and hold one meter lead to one coil lead (1). Touch and hold the other meter lead to housing (2).2. For correct operation, the resistance is 100 000 ohms or greater (meter reading 0.10 or greater).3. If the meter reading is LOW, the field coil is grounded. Replace the field coil.Stator Tests
Stator
(1) Leads. (2) Frame.Stator Winding Continuity Test
1. Connect the meter leads between each pair of stator leads (1) for a total of three readings.2. For correct operation, all three readings are approximately the same.3. If any two readings differ by 0.10 ohms or more, replace the stator.Stator Winding Ground Test
1. Put the multimeter on the 20M resistance (Ohms) scale. Check each stator lead (1) for a short to ground. Connect one meter lead to a stator lead (1) and touch the other meter lead to stator frame (2). Repeat for each stator lead (1).2. For correct operation, the resistance is 100 000 ohms or greater (meter reading 0.10 or greater) for each stator lead.3. If the meter reading is low, the stator is grounded. Replace the stator.Diode Trio Test
Diode Trio
(1) Single terminal. (2) Terminals.1. Put the multimeter on the diode scale. Connect the meter to single terminal (1) and one of terminals (2). Note the meter reading.2. Reverse the meter leads and note the meter reading.3. When correctly operating, the reading for one Step is OL and the reading for the other Step is .4 to .9 volts. If the readings are not correct the diode trio is open or shorted. Replace the diode trio4. Repeat Steps 1-3 for the other two terminals (2).Rectifier Tests
Rectifier
(1) Negative (-) diode clips. (2) Grounded heat sink. (3) Positive (+) diode clips. (4) Insulated heatsink.For the following tests all diode clips (1) and (3) must not contact any thing. Bend all diode clips (1) and (3) away from the studs. To check the diodes, it is not necessary to disassemble the alternator as far as shown.Positive