The power supply for the throttle control motor is provided to the ECM through a control relay. When the ignition switch is turned on, the relay works based on the ignition signal sent to the relay. Besides that, a battery voltage is provided to the ECM. Once the switch is deactivated, the ECM signals the relay to turn off and the battery voltage is no longer sent.
If the Engine Control Module detects that the power supply voltage to the throttle control motor is inconsistent, the P1126 OBDII fault code will be set. Note that for 2000-2001 Infiniti, this definition does not apply.