Bench Testing: Rectifier
WARNING: This page is about a different car, the 2003 Isuzu Rodeo Sport. However, it is still accessible from the selected car via links, so may be relevant.
Measure the resistance between each diode terminal and aluminum diode fin in forward and reverse directions with the connection of the tester leads switched. See Fig 1 . The diodes are normal if resistance is nearly zero ohms in one direction and is infinitely high in the other direction. If a diode has no resistance or equal resistance in both directions, it is defective and should be replaced together with the holder