Generator Current Control

When turning on headlamp or heating wire in idling, engine rpm will instantly fall down and then recovered due to increased generator load. At that time increasing electrical load will generate rapid engine rpm change, resulting to vibration and poor comfortableness.Generator current control system depends on engine ECU that controls current output from generator in order to prevent drop of engine rpm when inputting electrical load.
As for generator current control, Engine ECU duty-controls G terminal and consequently the current provided to rotor coil.
When duty level of G terminal is high, TR1 will be on and current at S terminal flow to ground, and zener diode will be off. Then TR2 will be off and then TR3 on. Therefore current will flow through rotor coil, and then generator operates to output current.
On the other hand when G terminal duty level is low, supply current at L terminal flows to engine ECU, turning TR1 off. Then if voltage between L and S terminal is 14.7V or higher, current will flow through zener diode, turning TR 2 on. Then, TR3 will be off and no current will flow through rotor coil, disabling power generation.
G terminal duty-control varies depending on target generating rate. Generated current will be calculated using time (on) of the FR terminal and engine rpm together. When time (on) of FR terminal and engine rpm rise, the duty rate of G terminal will increase to rise current generation.
Repeated control of G terminal performed by high rate duty operation as said above, will realize optimum current generation.
In order to measure FR signal, engine ECU provides 12V power supply at terminal B11, and connected with TR3 via wiring. When TR3 is on, say current flows through generator rotor coil to generator, voltage at FR terminal will drop to 0V (low level). On the contrary, if TR3 turns off, the terminal voltage will remain at 12V (high level). FR signal measurement will be decided by comparing and analyzing between generating period by generator, say period of FR terminal remaining at low level, and crank angle sensor.
You can check the actuator actual value and status and activate it when it is possible by AutoHex Automotive Diagnostic Scanner under the supported car brand and according to engine type.