Output Current Test

This test judges whether or not the alternator gives an output current that is equivalent to the normal output.
1. Ensure battery condition is in sound state and that the tension of the alternator drive belt is correct.

Fig. 2 Output Current Test:

2. Refer to Fig. 2 when preparing the charging system as follows:
a. Turn ignition switch to Off position.
b. Disconnect battery ground cable.
c. Disconnect alternator output wire from terminal "B".
d. Connect a 0-100 DC ammeter positive lead to terminal "B" and the negative lead to the disconnected output wire. Tighten all connections using suitable bolt and nut as a heavy current will flow. Do not relay on clips.
e. Connect a 0-20 voltmeter positive lead to alternator terminal "B" and negative lead to a sound ground.
f. Connect an engine tachometer then the battery ground cable.
3. Ensure voltmeter reads same voltage as battery.
4. Turn headlights On and start engine.
5. Set headlight on high beam and heater blower switch on high, quickly increase engine speed to 2500 RPM and read maximum output current indicated on ammeter.
6. Calculate output limit value. Limit value is equal to 70% of output rating listed under Specifications.
7. Ammeter reading must be higher than limit value. If reading is lower and output wire is satisfactory, replace alternator.
8. Normal output current value is shown in nameplate attached to alternator. The output current value changed with electrical load and temperature. therefore the normal output current may not be obtained if the vehicle electrical load, at time of test, is small. In such a case, discharge battery by leaving headlights on or by using another vehicle's lights to increase load.
9. After completion of test, set engine speed at idle and turn off lights and ignition switch.
10. Disconnect battery ground cable.
11. Disconnect ammeter and voltmeter then reconnect alternator output wire and connect battery ground cable.