Hello XXXXX'm Chris, a current Ford Lincoln Mercury employee.
Thanks for visiting Just Answer. I will do my very best to help you resolve your concerns.
2 or 4 door?
Where was the sensor located which you replaced?
Does the speedo work none at all or sometimes?
Any warning indicators on like ABS or check engine light or OD cancel switch light flashing?
Ok the speed signal does come from the rear sensor and normally this is a easy replacement sensor fix but not in your case. So you need to see if the sensor is reading or if the signal is not getting to the ABS module lost along the way or a concern in the ABS.