Q: Transmission in limp mode

The transmission control module (TCM) takes inputs from numerous sensors. It then uses this information to control various transmission related outputs such as shift solenoids and the torque converter clutch. The TCM will go into limp mode when it loses one of its main inputs, such as the transmission speed or transmission range sensor. It may also go into limp mode if there is problem with one of the main outputs, such as a shift solenoid, or if there are internal transmission mechanical problems. When in limp mode, the transmission control module (TCM) will cut power to the transmission control relay and de-energize the shift solenoids. This prevents the transmission to be limited to only 2nd or 3rd gear. I suggest calling a professional, such as one from YourMechanic, to diagnose and repair this problem for you.