The diodes are the electronic part of the alternator that convert AC voltage to DC. Switch your multimeter to the lowest AC setting and reattach the test leads to the battery.

We're going to answer all your questions about alternator replacement, repair, and the cost involved to do it yourself or have a pro handle it.

In operation, as the alternator’s rotor spins the magnetic poles change from north to south and as a result the current in the stator is constantly reversing direction, which produces ...