Transmission Control Switch (TCS)
WARNING: This page is about a different car, the 2005 Mercury Mountaineer and 2005 Ford Explorer. 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 located on the end of the shift control selector lever. Pushing the transmission control switch (TCS) will either disengage or engage the overdrive function of the transmission. If the overdrive ((D) ) is disengaged, the message O/D OFF will illuminate on the instrument panel.