Transmission Control Switch (TCS)
WARNING: This page is about a different car, the 2012 Ford Mustang. However, it is still accessible from the selected car via links, so may be relevant.
The Transmission Control Switch (TCS) is a momentary contact switch that is located on the transmission selector lever. Pushing the TCS disengages or engages the overdrive function of the automatic transmission. If overdrive is disengaged, the icon overdrive OFF illuminates on the Instrument Cluster (IC).