Alternator - Delco 27SI Caterpillar

Illustration 1	g00874988
Restoring the Residual Magnetism (1) Jumper wire

Reduced residual magnetism results in charging problems during start-up. Follow the procedure below in order to restore the residual magnetism of the alternator.

1. Connect the positive terminal of a 24 volt battery to the "B+" terminal of the alternator.

2. Connect the negative terminal of a 24 volt battery to the "B-" terminal of the alternator.

3. Connect one end of jumper wire (1) to the "B+" terminal.

4. Connect the other end of the jumper wire to the "R" terminal. A spark occurs as the jumper wire touches the "R" terminal. If a spark does not occur, the alternator has an internal open.

5. Wait for two seconds.

6. Disconnect the jumper wire from the "R" terminal.

   Expected Result: The residual magnetism is restored.

Alternator Residual Magnetism Loss

The residual magnetism is reduced by the following conditions:

• Dropping the alternator

• Handling the alternator roughly

• Storing the alternator at temperatures above 38 °C (100 °F)

• Storing the alternator for longer than 3 to 6 months

• Disassembling the alternator for repairs or for testing

• Having an alternator with poor manufacturing tolerances