What is this called ?

[2damslow]

What is this throttle body called in traditional toyota terms? And why would there be a separate switched relay power supply to it? 1991 prado 2Lte diesel. Thank you

 

[gnob]

not really sure what you're asking here. its called a throttle body.
but the egr and tps are also in the picture.
also not sure where you are coming up with the relay theory.
yes, that solenoid is likely behind key power, but its controlled ground side through a sensor or the ecu.