Sounds like you lost a speed sensor. It reads the vehicles speed at the transmission and the PCM uses the information to operate the speedometer as well as control the transmission. Do not drive it as it is, the transmission could easily be damaged.
The loss could be something simple like the wire came unplugged to the sensor or it may have broken or the sensor itself may have failed.
The first three pictures show the sensor on the four cylinder VTEC cars, it is on the right rear of the transmission. There is a very small piece that drives the sensor, if you opt to replace the sensor, be sure not to drop/lose it.
The other two pictures are for the V6 cars. They have a different style sensor that is touchy when installed.
Images (Click to make bigger)
SPONSORED LINKS
Friday, October 27th, 2017 AT 5:49 PM