Rectifier Test

NOTE: The diodes are designed to pass current in one direction and block current in the opposite direction. Since the alternator rectifier is made up of eight diodes (4 pairs), each diode must be tested for continuity in both directions; a total of 16 checks.


1. Using an ohmmeter or continuity tester (test light), check one diode from each pair, in both directions:


^ Connect POSITIVE test probe to B+ terminal and NEGATIVE test probe to P terminal of each diode pair. Note readings.

Rectifier Testing Hookups.:

^ Reverse probe position and check the diodes at P terminals again.

Rectifier Testing Hookups.:

2. Check the other diode from each pair, in both directions:


^ Connect NEGATIVE test probe to ground terminal and POSITIVE probe to P terminal of each diode pair.

Rectifier Testing Hookups.:

^ Reverse probe position and check the diodes at P terminals again.

Rectifier Testing Hookups.:

3. If any of the 16 checks shows continuity in both directions, or no continuity in both directions, the diode is defective and the rectifier assembly must be replaced. (Diodes are not available separately.)