Fatigued or broken wires to the output speed sensor can cause problems with the cruise control, erratic shifting, and speedometer operation. This may also cause Check Engine Light illumination.Google+
Car Problem Reports
Chrysler 300M Worn Wires to Output Speed Sensor May Cause Problems With Cruise Control/Shifting/Speedometer
Chrysler 300M Problem
Average Mileage: 144,533 mi (100,066 mi - 189,000 mi)
Visitor, 1999 Chrysler 300M, 189,000 mi
I was driving when the car stopped accelerating and then cut off. The RPMS goes up but the speedometer wont move at all.
Had what it seems to be a comon problem with input/output sensors, gears were not shifting on there own had to use autostick until problem was fix. But parts were not costly at all labor will be the exspensive thing.