Description & Operation

The generator has a built-in regulator with diagnostic functions and voltage regulating functions, such as the following:

1. Voltage regulation: The On-Off operation of transistor TR₁ connects and disconnects the field current circuit which provides a constant output voltage level. See Fig 1 .
2. Diagnosis warning is when any of the following problems occur the charge lamp illuminates:
   1. No voltage generation: Brush wear exceeds specified wear limits, field coil circuit is broken, etc.
   2. Excessive output: Output voltage is greater than 16 volts (approximately.)
   3. Terminal B disconnection: Harness is disconnected from alternator terminal B.
   4. Terminal S disconnection: 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 overcharging.

Fig 1: Generator Circuit Diagram

Courtesy of SUBARU OF AMERICA, INC.