Rectifier Diode / Bridge: Testing and Inspection

Rectifier Test (Nippondenso Alternator):

NOTE: The diodes are designed to allow current to pass in one direction while blocking it in the opposite direction. Since the alternator rectifier is made up of eight diodes (four pairs), each diode must be tested for continuity in both directions with an ohmmeter that has diode checking capability; a total of 16 checks.

1. Check for continuity in each direction, between the B and P, and between the E (ground) and P terminals of each diode pair. All diodes should have continuity in only one direction.

2. If any of the eight diodes fails, replace the rectifier assembly. (Diodes are not available separately.)