the button

[blazein]

OK Really basic question here but if you dont ask its even dumber. 1987 325is
I see a performance button under the gas peddle I know it works but am unclear as to why, rather what and how this thing works? The manual seems not to cover it unless I am missing the correct terminoligy for this switch. By your leave could someone please tough it out and help me to understand the form and function of this cool litle gizmo? Thanks, Dad and son

[drz]

Do you have an automatic? In that case, it is probably the downshift button, which prompts the transmission to downshift when you need that extra torque right away, like for passing cars, etc.

[blazein]

Yes the car is an Auto 1987 325is as stated above I thought the button worked as you could hear it clicking. Sadly I was mistaken. So now to embark on the trouble shooting path. Is this an electrical switch? does it run to the tranny or to another sensor on the car? And last is there a standardize method to systematically trouble shoot it. Thanks,Dad & Son