Output Test

Ensure alternator drive belt is properly adjusted and battery is fully charged before performing the following procedures.
1. With ignition switch in Off position, disconnect battery ground cable.





2. Disconnect wire from terminal B of alternator, then connect an ammeter between battery ground cable and alternator B terminal, Fig. 3.
3. Connect a voltmeter between B terminal and ground.
4. Connect battery ground cable to battery ground post and note voltmeter reading. Voltmeter should indicate battery voltage.
5. Connect a tachometer to engine, then start engine and turn on lights.
6. Operate engine at 2500 RPM and note ammeter reading. Reading must be higher than limit values, given below:
a. On 65 amp alternators, limit value should be 45 amps minimum.
b. On 75 amp alternators, limit value should be 52.5 amps minimum.
c. On 90 amp alternators, limit value should be 53 amps minimum.
7. If reading is lower but alternator output wire is normal, then remove alternator for bench testing.