Transmission Control Switch (TCS) and Transmission Control Indicator Lamp (TCIL)
WARNING: This page is about a different car, the 2004 Ford RV Cutaway, 2004 Ford Econoline, and 2004 Ford Cutaway. 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. When the switch is pressed, a signal is sent to the PCM to allow automatic shifts from first through fourth gears or first through third gears only. The PCM energizes the transmission control indicator lamp (TCIL) when the switch is off. The TCIL indicates overdrive cancel mode activated (lamp on). When the TCIL is flashing, it indicates electronic pressure control (EPC) circuit shorted or a monitored sensor failure.