Subaru 2002 Impreza Service Manual page 213

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GENERATOR
Starting/C harging
2. Generator
The generator has a built-in regulator which provides diagnostic functions in addition to a voltage
regulating function as follows:
1) Voltage regulation
The on-off operation of transistor Trl connects and disconnects the field current circuit, providing
a constant level of output voltage.
2) Diagnosis warning
When any of the following problems occur, the charge lamp illuminates.
a. No voltage generation
b. Excessive output
c. Terminal B disconnection
d. Terminal S disconnection
Brush wear exceeds specified wear limits, field coil circuit is broken, etc.
Output voltage is greater than 16 volts (approx).
Harness is disconnected from alternator terminal B.
Harness is disconnected from alternator terminal S. In this case, voltage is slightly greater than
specified regulated voltage; however, voltage regulation is still controlled and the battery is
prevented from becoming overcharged.
r -
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Plus diode (3 pcs.)
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Trio diode (3 pcs.)
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Tr2
Diagnostic
and warning
circuit
IC regulator 0
:Alternator terminal
0
: Regulator terminal
Minus diode (3 pcs.)
NF0365
sc-3