Chrysler Repair: 1999 300M Limp Mode and no speedo, 4 digit numbers, chrysler warranty

Question
My 1999 300M has 67000 miles on it.  Just recently went into the 2nd gear limp mode, 'check engine light came on and the speedometer quit working.  This also happened about 34000 miles ago (about 4 years).. chrysler warranty covered it.  I am a 78 yr old retiree, pretty good with tools,etc.
Can you point me to areas I might be able to check w/o having to go to dealership .. thanks

Answer
Hi Ralph,
That has all the signs of the distance (or "output speed") sensor on the automatic trans having failed. It is located on the driver's side at the very far end of the unit. It has a twin up at the torque converter end, at the same level on the unit, so that would be a way to know you have found it. Simply lift tab on connector, unscrew, screw in the replacement to about the same torque as a spark plug and that should correct the speedo and the limp. You can verify with a code readout for free at an Autozone parts store, or try the ignition key:"on-off-on-off-on and leave on" doing that in 5 seconds or less elapsed time. Then see if any 4-digit numbers replace the mileage setting in the odometer window. Let me know, and we can verify my diagnosis that way.
Roland