Kickdown Switch
 

What is Kickdown Switch for?
Ths.

to electrically initiate a downshift when the throttle is floored. The combined effect of kickdown and control (throttle) press can cause a drop of two gears.

Why and when is it needed?

The cable will only drop one gear on the auto tranny! The kickdown switch activates the kickdown solenoid which forces the tranny to drop to the lowest possible gear! Example: On my 190E my tranny will shift at 4000 RPM from 1st to 2nd when floored but the kickdown not activated! If I floor it to the kickdown I get a shift at redline! At 65+MPH my tranny will not downshift to 3rd unless I hit the switch, make pasisng a little better when you can actually accelerate! The cable portion of the tranny kickdown only drops a single gear, so if you are going 20MPH and hit the gas you will only drop to 3rd instead of 2nd! Well at 20 3rd is kind of a waste! On my W203 the kickdow is a hair diferent since that has an electronic throttle and is also a 6 speed! It acts to not only downshfit the auto tranny, but also to tell the ECU that you are at WOT!