On Car Test
Connect alternator as shown in illustration. Check that current through field winding (rotor) is 3.5 amps. If current is not 3.5 amps, check field winding condition and brush holder. Run engine speed to 3000 RPM. Alternator should then produce the specified current. Measure voltage at terminal "B+" and at terminal "61". Voltage should be 0.8 - 0.9 volts more at terminal "61". If not, isolation diodes are faulty and should be replaced.