Subaru 2009 IMPREZA Service Manual page 414

STARTING/CHARGING SYSTEMS
E: INSPECTION
1. DIODE
CAUTION:
There is the possibility of damaging the diodes
if a mega-tester (used to measure high voltag-
es) or a similar measuring instrument is used.
Never use a mega tester or equivalent for this
test.
1) Check the positive diode
Check for continuity between the diode lead and
positive side heat sink. If resistance is 1
only in the direction from the diode lead to the heat
sink, the positive diode is OK.
(A)
(A) Diode lead
(B) Heat sink (positive side)
2) Check negative diode
Check for continuity between the negative side
heat sink and diode lead. If resistance is 1
only in the direction from the heat sink to the diode
lead, the negative diode is OK.
(A)
(B)
(A) Diode lead
(B) Heat sink (negative side)
Generator
or less
(B)
SC-00042
or less
SC-00043
SC(H4SO)-20
2. ROTOR
1) Slip ring surface
Inspect the slip rings for contamination or any
roughness on the sliding surface. Repair the slip
ring surface using a lathe or sand paper.
2) Slip ring outer diameter
Measure the slip ring outer diameter. Replace the
rotor assembly if the slip ring is worn.
Slip ring outer diameter:
Standard
22.7 mm (0.894 in)
Limit
22.1 mm (0.870 in)
3) Continuity test
Using a circuit tester, check the resistance between
slip rings.
If the resistance is not within the standard, replace
the rotor assembly.
Specified resistance:
Approximately 1.8 — 2.2
4) Insulation test
Check the continuity between slip ring and rotor
core or shaft. If the resistance is 1
place the rotor assembly because the rotor coil is
grounded.
5) Ball bearings (rear side)
Check the rear ball bearing. If there is any noise, or
the rotor does not rotate smoothly, replace the
bearings.
SC-00044
or less, re-
SC-00045