VC Output Circuit [08/2013 - 08/2016]: Description
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2019 Toyota Corolla, 2018 Toyota Corolla, 2017 Toyota Corolla, 2016 Toyota Corolla, and 2015 Toyota Corolla. However, it is still accessible from the selected car via links, so may be relevant.
The ECM constantly generates a 5 V power source voltage from the battery voltage supplied to the +B (BATT) terminal to operate the microprocessor. The ECM also provides this power source voltage to the sensors through the VC output circuit.
When the VC circuit is short-circuited, the microprocessor in the ECM and the sensors that are supplied with power through the VC circuit are inactivated because power is not supplied from the VC circuit. Under this condition, the system does not start up and the MIL does not illuminate even if the system malfunctions.
HINT:
Under normal conditions, the MIL is illuminated when the ignition switch is turned to ON. The MIL goes off when the engine is started.