Hi,

Electronic Throttle Control Module is a component of the Engine Management.On these cars there is no direct connection between the accelerator pedal and the throttle butterfly. When you press the gas pedal you send a signal (by varying the resistance of a potentiometer) to the Engine Management Unit's computer which then looks at engine load, air temperature and engine temperature and sends a signal to the ETC Module to open the throttle butterfly by the appropriate amount. If you were really nit picking it could be considered as part of the emissions system but then so can almost any part of the fuel inkection system. In my view if it is possible for the engine to run without a component of the injection/exhaust system then it is an emissions component. In this case the engine will not run without it so imho it is not an emissions component.... As for other components that use it.... traction control systems and cruise control both use the TCM... good luck arguing...

As a footnote, the Throttle Control Module on my car was playing up and I managed to get it working again by removing it, taking off the covers and giving it a good blast out with an electrical contact cleaner.

As for replacing it.... it requires the ECU to be reset by a dealer so its not an easy job....