Speedometer runs but odometer dont; on 1993 Crown Victoria

Did you check for a fuse

if the odometer does not stick, watch carefully , the 1/10s digit.
drive slow, no bumps when it sticks and watch ODOMeter
if odometer dont stick the needle side is, as all do this old.
for 90s cars, vast numbers stick and more every day
as owners hedge , gee $200 fix .or more.......
get a GPS speedo and use that, or glue on a cell phone holder
and use a free app, (GPS speed) to see speed.
there you go, all choices.
the cable has 2 ends.
head end if dead, the speedo and odometer stall.
the other end, has gear to trans tail shaft,
so it measures actually road wheel RPM and converts that to speed.
the cable can be broken on both end or the middle.
the bottom end can fail strip out or its gear go bad.
fixed them all, every which way but loose.
easy no? easypeasy-japaneezey
if the odometer freezes too, that means the cable end is bad.

You need to change your cable that goes to your transmission from the odometer easy fix

Phylspilot, my 86 Spider never displayed less than 10 mph. If you look closely, you should see a tiny pin that the needle touches at about 10 mph. That prevents it from ever falling to zero. The needle will not move up until the speed exceeds 10. From my experience, that is normal. In your case, not displaying >20 is NOT normal.

The problem could be a few different things. Since the odometer appears to be working ok (I assume you checked that it racks up the miles at a rate commensurate with your approx speed), the speed needle may be sticking. I had the opposite problem with mine - speed needle okay, and odometer messed up.

I recommend pulling the speedometer housing out of the dash and checking to see if anything is causing the needle to bind. If it isn't, then check the fine spring where the needle is attached to ensure the spring is okay. You should be able to move the needle with your finger smoothly and have it return gently to the start position (in your case 12 mph).

This is a tricky operation. If you remove the needle from the stem, carefully place it back on the stem. Do this without moving the stem. Just reinsert the speed needle on the stem exactly at the small pin that holds the pin at about 10 mph.

Check the entire speedometer housing for cracks. Any crack could be enough to prevent proper operation. (That was the source of my odometer issue.)

Have fun putting it all back together.

No cable, it's electric. Run by a sensor on rear of transmission.

if the speedo is not sending a speed the trans will go into back up mode and the trans will not shift normally check the speed sensor

Did you check the fuse?

Both run off the speed sensor so if one is working and the other is not it's got to be in the instrument cluster.

Either the speed sensor,or the dash cluster is of fault. Have Auto Zone test the speed sensor,if ok ,,, I would replace the cluster ( buy used ) much cheaper.
Please rate this.

most likely the speed cable broke.

Dave