Scotty, i have some cleaning on my sister's toyota yaris 2009 electronic throttle body, i can hear a…

Scotty, i have some cleaning on my sister's toyota yaris 2009 electronic throttle body, i can hear a hissing sound when i ask somebody to step on gas to make the throttle plate open with my key in "on" position, is this normal, izzit going to hurt anything with that sound?once i off switch my key to "off" position, the sound gone, pls advice, ty

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