Metro L4-079 1.3L VIN 9 TBI (1995)
Voltage Signal: Description and Operation
System Voltage
SYSTEM VOLTAGE SIGNAL
The fuel injector is driven by its solenoid coil based upon the Engine Control Module (ECM) output signal.
There is some delay called "Ineffective Injection Time," where no fuel is provided, between the ECM signal and valve action.
Since ineffective injection time depends on the system voltage, the ECM takes voltage information to compensate for fuel injection time.