No speedo/no shift

My girl came home tonight and said her 2000 Caravan engine light stays on, speedo quit, and it won't shift out of maybe 2nd gear ??

How do I read the codes, and what might be the problem ?
Thanks

most likely output speed sensor,easy to replace

earlyrizr is right on both counts but, if you still want to see the codes go to Autozone where they will read the code with a DRB II scanner for free. Should see a P0500 code.

The Vehicle Speed Sensor is the signal source for the speedometer and is involved in shift scheduling for the transmission. The symptoms you have are a dead giveaway.

Your transmission went into what is called the limp mode because a sensor failed. It's a failsafe mode that limits the gear range to 1st and 2nd gear to "save" the transmission.

That might be true, but I can't seem to find the sensor. I took 1 out that had a different thread size than the new sensor I got. I did find out I have a broken trailing arm though.

This is based on a picture of a 98. Find where the dipstick enters the tranny. Just to the right, between the small lines leading to the cooler is the input speed sensor. Keep going about six inches straight to the right and that is your output speed sensor.