Whenever a transaxle goes into 'limp-in', it will shift to a default gear (like 2nd gear) instead of stranding you. 2nd gear is a hydraulic/mechanical gear range, which means that it does not depend on any electronics to select 2nd gear.
As a 'failsafe', it will get you home or to a shop in the event of electronic failure.
At the same time, a fault code should be stored in the PCM or TCM (transaxle control module) and it may light the yellow 'ck engine' light. This fault code(s) should stay in PCM/TCM memory for 40-50 key starts. Even if the dash light goes out, the code(s) should still be stored. Begin by getting the fault code(s).
If you can't get the code to display in the odometer with the 'key dance', then you may need to read the code with a scan tool. Many auto parts stores will read codes for free. An OBDII engine code reader may or may not display transaxle codes as these codes may not be considered 'emissions' -related.
Turning the key off, then back on may reset the TCM. It may come out of limp-in, but the code(s) should still be stored in memory.
For known problems, many can be fixed with a non-invasive software update. Periodic ATF+4 and filter changes allow the pan bottom and magnet to be inspected as a baseline for tranaxle 'health'.
The car may not have a dipstick (I use a length of old speedometer cable and a temperature chart). Don't just add ATF if you aren't sure of the level. Overfilling can be just as bad. Use ATF+4 meeting Chrysler MS-9602 only. No Dexron or Mercon fluids. Do not mix fluids.
The only way for ATF to be low is if you have an oil leak. If the pan and cooler hoses under the car are dry, the level is probably OK.
Always diagnose first. Even the best guesses can be frustrating and expensive.
Some TSB examples: