Have a 3.0 Liter 99 Taurus with an automatic transmission. While driving in traffic on a hot day, the following symptom occurred:
The speedometer and odometer stopped working
The Overdrive off dashboard light started flashing
Automatic shifting became erratic
OBD code indicated 500 ? Vehicle speed sensor malfunction
Symptoms went away the next day, but reappeared when the vehicle is driven in traffic on a hot day.
Is the solution as simple as replacing the vehicle speed sensor?
Where is this located on a Taurus? All that I?ve been able to find is that it is mounted on the transmission.
Can the average backyard mechanic with jack stands replace it or should I bring it in?
I would say that the solution could be as simple as the VSS, but it could be simpler still and you could have a problem in the connector AT the VSS. All of the symptoms you describe point to that component (the confirmation being your speedo problem), but the fact that it is only intermittent could well be a wiring issue.
Unfortunately I haven’t been under the hood of a Taurus of that vintage, so I can’t tell you how easy it is to get to, but that car has an AXODE transaxle and they are always on the left-most (when facing the front of the car) side of the transaxle housing. Where the passenger-side axle shaft goes in to the transaxle, there will be a sensor on the housing there. That is the VSS. Assuming you can get your hands on it, replacement is a piece of cake. Only a couple of bolts. Good luck with it!
You can do it. I’d like to thank Auto Zone Auto Parts (www.autozone.com) for providing a very useful web site: WIRING DIAGRAMS, how-to articles, parts, and so much more. For your car, go to www.autozone.com, click on: Manage My Vehicles > Remove > Add a Vehicle > select year (1999), make (Ford), model (Taurus), engine (6 cyl or 8 cyl). Click on: Shopping, parts > in Product Search block, put vss > go > select vss (vehicle speed sensor) based on the number of bolts holding the transmission oil pan (either 17 or 19 bolts) > see picture and price(s). Now, you have the part. For the how-to, go to: Repair Info and click on Vehicle Repair Guides > Driveability & Emissions Controls > Electronic Engine Controls > Vehicle Speed Sensor yields vss Operation, Testing, and Repair and Replacement. +++ It is confusing as to which black component is the one you want on the engine. One way is to follow the wires. From the WIRING DIAGRAM (on that same site) the wire colors for the vss are: pink/orange and gray/black. The /color can be a stripe, a dash, a hash mark, or dots. +++ Anyone can go to www.autozone.com for information which can, otherwise, be very difficult (or, impossible) to obtain about their car.
Thank you both for the excellent answers.