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.

Alternator Repair Cost In some instances, your faulty alternator might require minor repairs instead of a full replacement. You may need a new belt or to clean the electrical connecting points.