Note: Diodes allow current to flow in one direction and prevent it from flowing in the opposite direction. Since the alternator rectifier consists of eight diodes (four couples), it is required to test the conductivity in both directions with an appropriate ohmmeter; a total of 16 checks.
1. Perform a continuity test in each direction between:
Terminals B and P
Terminals E (Earth) and R
All diodes should only conduct in one direction.
2. If any of the diodes fail, replace the rectifier assembly (diodes are not supplied separately).