Transmission Control Switch (TCS)
WARNING: This page is about a different car, the 2010 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 will disengage or engage the Overdrive (O/D) function of the automatic transmission. If O/D is disengaged, the icon O/D OFF will illuminate on the Instrument Cluster (IC).