Output Current Test

TEST PROCEDURE
1. Disconnect battery ground cable.
2. Disconnect "B+" lead at alternator output terminal.

Fig 6 Alternator Current Output Test:

Fig 7 Alternator Current Output Test:

3. Connect a 0-150 amp D.C. ammeter in series between alternator "B+" terminal and disconnected "B+" lead wire.
4. Connect positive lead of a suitable voltmeter to "B+" terminal of alternator, then connect negative lead to suitable ground.
5. Connect a suitable engine tachometer, then reconnect battery ground cable.
6. Connect a variable carbon pile rheostat between battery terminals, ensuring carbon pile is in Open or Off position.
7. Remove air hose between Engine Controller and air cleaner.

Fig. 4 Alternator Connections (Plug Type):

Fig. 5 Alternator Connections (Nut Type):

8. Connect suitable jumper wire to ground and K20 (field driver) terminal, at rear of alternator. This may generate a fault code. Do not connect power field circuit to ground, as component damage will occur.
9. Start engine and operate at idle speed, then adjust carbon pile and engine speed in increments until a speed of 1250 RPM at 15 volts is obtained. Do not allow voltmeter range to exceed 16 volts during inspection.

TEST RESULTS
1. Note ammeter reading.
2. If reading is less than specified and alternator wire resistance is not excessive, alternator is defective.
3. After completion of current output inspection, turn off carbon pile and ignition switch, then disconnect battery ground cable.
4. Remove ammeter, voltmeter, tachometer and carbon pile, then reconnect "B+" lead to alternator output terminal.
5. Disconnect jumper wire, then connect air hose from Engine Controller to air cleaner.
6. Connect battery ground cable.
7. On models quipped with on board diagnostics, erase codes using DRB test tool or equivalent scan tool.