My 99 cougar wont shift through the gears and the speedometer will not register the speed.

SOURCE: 1999 ford taurus transmission

Your problem is the speed sensor. The VSS (vehicle speed sensor)

is located on the right side of the transaxle, near where the right side axle shaft

connects to. To access this part is pretty tricky, if you are inexperienced. There

is an aluminum foil covered shield around the wiring connector. You will need to

remove the shield to gain access. You may even have a damaged wiring

connector, that is causing the problem due to the close proximity of this part to

the catalytic converter. If you want to purchase this part from the Ford dealer,

ask the parts counter person for the "basic" part number 9E731. Hope this helps.

SOURCE: the transmission wont shift out of 2nd gear again.

i can answer part of your question. the front wheel speed sensors are for abs and trac control only. these will not affect the speedo your problem is some where else. sorry i have not had this prob yet good luck. you could have to replace the rear wheel speed sensor again. they are not that good. and after market are even worse.

SOURCE: vehicle speed sensor

You will have to get to it probably from under the car it will be located just to the right of the driver's side axle

SOURCE: speedometer doesn't work and transmission wont shift

Hi, make sure you check the speed cable that runs to the engine, it may be severed. As for the tranny, you have some major gear problems that will require pulling this transmission for a deeper look. i would have a look at the transmission filter as well.

SOURCE: Speedometer sensor/cable needs replacing

try looking at the book theres a cable from the transmit ion to the speedometer and it could be a bad connection or theres a gear in you're trans that spins and tells how fast you're going sometime those go out haven't had that problem yet but i built my truck from the ground up