1999 Ford Taurus - Speedometer drops to zero and trouble shifting

[Dave_s]

1) stand on the drivers side of the car by the fender

2) use a flashlight to look into the engine at an angle. Under cylinder two is the speed senor.

3) reach in and unhook the cable from the sensor

4) use a 10 millimeter ratchet with a short extension to undo the bolt. Be careful not to lose the bolt.

5) pull the sensor out towards you.

After you have the sensor out, you need to remove the rubber thing on the tip (a gear). It has a retainer clip holding it on. Be careful not to lose the retainer clip.

The hardest part is getting the bolt back in after you put in the new sensor.

One thing to note is that both the Haynes manual and the Taurus shop manual tell you to get at t from under the car. I still can't figure out how one would do that.

[krisci3]

I would suggest bringing to a transmission shop. My '98 Duratec was doing the exact same thing. They examined for free. It was the VSS, they replaced for $315. The old one came out in pieces as it was rusted so badly. I wouldn't even attempt to mess with this one myself. Know your limits!

[Vilita]

Originally Posted by krisci3

I would suggest bringing to a transmission shop. My '98 Duratec was doing the exact same thing. They examined for free. It was the VSS, they replaced for $315. The old one came out in pieces as it was rusted so badly. I wouldn't even attempt to mess with this one myself. Know your limits!

Bollocks.

I fixed it myself and spent $15.99

Its not the easiest part to locate, but here is my advice.

1) Take off the right front tire. You will see a round tube shaped part of the car with a metal clip around it, this is the clip for the heat shield. Just pop off the heat shield, because you won't be able to see the VSS until you do that.

2) Follow the steps above

3) The way I found easiest was putting a piece of cardboard over top of the engine and just lying down over the engine, I brought a mirror with me, located the VSS and that was it. Just get the bolt off, pop it out, swap the end to the new part and screw it in.


The hardest thing was trying to get a clear description of where on the car it was, as everyone seemed to think it was in a different place. Once I located it for myself, it was relatively simple, and I saved $300.

[rdh2]

Originally Posted by angus10

Well thats BS! Go to a different dealer then! The vin# provides every detail about your vehicle down to the lug nuts.

Actually, the VIN does not provide transmission information. The transmission code is located on the label on the drivers door in the block labeled TR, which is item 9 in the picture.

Code T or L is an AX4S and Code X or N is an AX4N.

[shorod]

Right. The VIN actually provides suprisingly little data as to the options and build data of the car. That's what a "build sheet" is for.

Straight from Ford, their VIN provides the following:
Position 1-3 World Manufacturer Identifier
Position 4 Restraint System Type [Brake Type and GVWR Class (Trucks and Vans Only) ]
Position 5-7 Line, Series, Body Type
Position 8 Engine Type
Position 9 Check Digit
Position 10 Model Year
Position 11 Assembly Plant
Position 12-17 Production Sequence Number

-Rod

[mchance379]

I have the same problem with my 99 taurus, but my odometer stops counting when the speedometer drops to zero, and occasionally the tachometer drops to zero also. Would the vehicle speed sensor also cause this problem or would something else possibly be wrong?

[shorod]

Welcome to the forum! The VSS would not cause the tachometer to drop to zero. That would either be an issue in the instrument cluster common to both gauges, or the Camshaft Position (CMP) sensor has an issue. The tach signal is sourced from the CMP sensor.

-Rod

[eoakley]

@shorod

You are clearly a pro at this, especially this model. Thank you very much for spending your time here helping us!

I experienced the zero MPH symptom today while driving home, and my car wouldn't shift from 1st. Suddenly the speedometer started working again, and it shifted. I feel my problem is the sensor you mentioned above, and plan to take the steps to replace it.

A side question:
Would a faulty sensor of this type also cause "jerky" behavior while cruising in OD?

[shorod]

Welcome to the forum!

Yeah, a faulty VSS could cause jerky behavior when in OD because the computer is only supposed to let the OD engage at sustained speeds above something like 35 mph. If the VSS drops out momentarily, the PCM will probably try to disable the OD which you may feel as a jerkiness.

-Rod

[eoakley]

@shorod

This makes so much sense. Hopefully I will be able to replace this sensor this weekend.

I have been monitoring my gauges knowing what I now know, and have noticed the speedometer slightly jumps or lags very seldom. I would not have noticed it before, but now I know what to look for.

Something new happened. I was driving for over an hour, then went to a store and turned off the car. When I started it again and left the store, it would not shift from 1st gear. Then on the cluster, a green light flashed that reads 'O/D OFF'. I understand this cluster was probably used in several different models, as I don't have the ability to disable O/D. Actually I don't think my car even has O/D.

So my question is does this flashing 'O/D OFF' indicate anything else, or would it still lead to the same sensor?

Thanks again for all you do here!

[shorod]

What year is the Taurus you have, and do you know which transmission it has (see post #19 above)? I would be quite surprised if your car does NOT have OD and if you are not able to turn it off. Do you have an owner's manual for the car?

That being said, the flashing likely indicates that the transmission has identified an issue and set a diagnostic code. Unfortunately since the OD Off light is flashing rather than the Service Engine Soon / Check Engine light, the common consumer-grade scan tools will not be able to retrieve the transmission diagnostic code. That will instead require a professional scan tool. There are far too many possible issues that could cause the car to remain in first (or more likely 2nd) and set the OD Off light to flash to speculate without know what the code is. If that happens again (or is still happening) you might try manually shifting between the low gears to see if the gear select lever will allow you to access different gears.

-Rod

[Willyum]

Determining what engine is in a Taurus is not rocket science. It is important to know when working on one.

[scott1417]

One quick note in replacing vss 1998 Ford Taurus 3.0 DOHC AX4N 19 bolt. I was able to get it from under the passenger side with car jacked up you can get one hand on the bolt and with the other reach up through the a-arm and reach around the alternator, use a small ratchet with a deep socket and 1 small extension. Worked for me, good luck!