CARRIER 3K9405 - Caterpillar

Battery Circuit Test
Condition: Engine not running; oil pressure switch open.1. Connect test ammeter between alternator POSITIVE OUTPUT terminal and battery positive terminal. Test ammeter remains in the same position throughout all the tests.2. Connect voltmeter positive lead to battery positive terminal, negative lead to battery negative terminal. Read voltages. Correct voltage on 12 volt system should be 12.0 to 12.6 volts, on 24 volt system, 24.0 to 25.2 volts.3. Move voltmeter positive lead to battery side of oil pressure switch. Leave negative lead on battery negative terminal. Read voltage. Then move positive lead to alternator POSITIVE OUTPUT terminal. Read voltage. Voltages should read the same as in Step 1. If voltage is lower, check and repair cables, leads or terminals as required.4. Ammeter should read zero at all times during these tests. If ammeter reads down scale, it indicates a shorted diode in the alternator.Control Switch Positive Diode Test
Condition: Engine not running; oil pressure switch open.1. Connect positive lead of voltmeter to alternator TACHOMETER terminal, negative lead to battery negative terminal. Voltmeter should read zero. If voltmeter reads above zero, one or more of the positive rectifier diodes in alternator is shorted.2. Connect voltmeter positive lead to alternator side of oil pressure switch, negative lead to battery negative terminal. Voltmeter should read zero. If voltmeter reads above zero, oil pressure switch may be shorted.3. Test ammeter should show zero throughout these tests.Rotor (Field) Current Draw Test
Condition: Engine not running; oil pressure switch open.This test requires temporary addition of test carbon pile to battery to reduce voltage to reference level and a field rheostat.1. Turn load control knob of carbon pile to OFF position and connect leads to battery.2. Remove lead from No.1 FIELD terminal of alternator.3. Place field rheostat knob in maximum resistance position; connect leads to No.1 FIELD terminal and POSITIVE OUTPUT terminal of alternator.4. Connect test voltmeter negative lead to NEGATIVE OUTPUT terminal of alternator, positive lead to NO.1 FIELD terminal.5. Read all test instruments. Carbon pile voltmeter should read battery voltage. Ammeter should read zero amps. Test voltmeter and test ammeter may indicate near zero depending on resistance value of field rheostat.6. Slowly decrease resistance of rheostat to zero. Test voltmeter will indicate battery voltage. Ammeter will indicate current draw of rotor (field winding). If ammeter reads excessive current (more than 5 amps) reverse rheostat to maximum resistance. This indicates a short. Disconnect leads and inspect brushes and rotor circuit for cause of high current draw.7. Slowly apply carbon pile load to battery until test voltmeter reaches reference point shown in table. Check test ammeter for rotor (field) current draw; it should be within limits shown in table. 8. If field current draw falls within the limits shown, rotor winding is good. If field current exceeds the maximum, alternator should be bench tested. Check for defective or dislocated brushes, shorted brush leads, foreign material between slip rings or shorted rotor (field) winding.9. Turn off carbon pile load immediately after test to avoid discharging battery.Regulator Load