MIL Circuit [08/2013 - ]: Description
WARNING: This page is about a different car, the 2014 Lexus ES 300h. However, it is still accessible from the selected car via links, so may be relevant.
The MIL (Malfunction Indicator Lamp) is used to indicate vehicle malfunctions detected by the ECM. When the power switch is turned on (IG), power is supplied to the MIL circuit, and the ECM provides the circuit ground which illuminates the MIL.
The MIL operation can be checked visually: When the power switch is turned on (IG), the MIL should be illuminated and should turn off after power switch on (READY). If the MIL remains illuminated or is not illuminated, conduct the following troubleshooting procedure using the Techstream.