Rectifier Test
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 sixteen checks.
1. Check for continuity in each direction, between the
B and P, and between the E (ground) and P ter-
minals of each diode pair. All diodes should have
continuity in only one direction.
E (GROUND)
2. If any of the eight diodes fails, replace the rectifier
assembly. (Diodes are not available separately.)
Alternator Brush Inspection
1. Remove the end cover, then take out the brush
holder by removing its two screws.
2. Measure the length of the brushes with a vernier
caliper.
Alternator Brush Length:
Standard: 10.5 mm (0.41 in)
Service Limit: 3.5 mm (0.14 in)
ALTERNATOR BRUSHES
VERNIER CALIPER
If the brushes are less than the service limit,
replace the assembly.
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 sixteen checks.
1. Check for continuity in each direction, between the
B and P, and between the E (ground) and P ter-
minals of each diode pair. All diodes should have
continuity in only one direction.
E (GROUND)
2. If any of the eight diodes fails, replace the rectifier
assembly. (Diodes are not available separately.)
Alternator Brush Inspection
1. Remove the end cover, then take out the brush
holder by removing its two screws.
2. Measure the length of the brushes with a vernier
caliper.
Alternator Brush Length:
Standard: 10.5 mm (0.41 in)
Service Limit: 3.5 mm (0.14 in)
ALTERNATOR BRUSHES
VERNIER CALIPER
If the brushes are less than the service limit,
replace the assembly.