Alternator - Bosch K1/N1 Caterpillar

Positive Diode Check

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Illustration 1	g03224496
Positive diode check (1) Positive (+) diode

1. Put the multimeter on the diode scale. Connect the multimeter leads between each Positive (+) diode (1) and the B+ stud. The positive diodes are in black color.

2. Record the multimeter reading and reverse the multimeter leads.

3. One reading should be "0L" and the other reading should be .4 to .9 volts. If both readings are "0L" or low (0 to .1 volts), the diode is open or shorted, and the rectifier must be replaced.

Negative Diode Check

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Illustration 2	g03224556
Negative diode check (2) Negative (-) diode

1. Put the multimeter on the diode scale. Connect the multimeter leads between each negative (-) diode (2) and the surface of the rectifier that is not painted. The positive diodes are in silver color.

2. Record the multimeter reading and reverse the multimeter leads.

3. One reading should be "0L" and the other reading should be .4 to .9 volts. If both readings are "0L" or low (0 to .1 volts), the diode is open or shorted, and the rectifier must be replaced.