Circuit description

WARNING: This page is about a different car, the 2014 Subaru BRZ. However, it is still accessible from the selected car via links, so may be relevant.

The engine control computer constantly produces 5 V from the battery voltage applied to +B terminal and +B2 terminal to operate the CPU. In addition, the engine control computer supplies this power to the sensor via VC output circuit.

Fig 1: VC Power Supply Circuit Block Diagram

Courtesy of SUBARU OF AMERICA, INC.

When the VC circuit is shorted, the power is not supplied from the VC circuit. Because of this, the CPU in the engine control computer and the sensors supplied from the VC circuit are de-energized. In this state, the system is not started, and the MIL does not illuminate even if the system malfunction occurs.

NOTE: Normally, when the ignition switch is turned to ON for the first time, the MIL illuminates. When the engine has started, the MIL goes off.