Ultimate Guide to: Replacing your VSS 1999 and newer Windstars


olopezm
06-26-2011, 06:20 PM
Hello people!

Well I just wrote my second guide to give back to the automotive forums and it's users a little of the help I've received. This time I will show how to replace the VSS on 1999 and later windstars with AX4S transmissions.

Although I'm not pretty sure it should apply to AX4N transmission too, the only difference is the orientation of the sensor; in AX4S transmission it is vertically oriented while in the AX4N it is horizontally. Maybe some other user can comment about it.

You won't need any special tools and won't have to deal with rusty exhaust bolts, motor mounts, etc. It's pretty straight forward.

You can get ahead of time and buy/order the VSS compatible with '99 and above windstars.

NOTE: You can click on each image for a larger resolution version of it. The last two links will take you to a couple of videos showing the sensor.

Remove the negative battery terminal before you attemp anything else.

First of all you need to remove the wiper blade arms using a 15mm socket. It's easier to remove them when the hood is still in the closed position.

Second you need to remove the wiper cowl, it takes 4 plastic phillips head screws with their respective holding clips at the bottom and once you've done that, you need to carefully pry the four plastic clips that hold the upper part of it, make your way from the upper corners to the center of the cowl, do this carefully because those tabs can break very easily. Take your time! Once it's loose you'll need to alternate between opening and closing the hood to get it out through the backside towards the windshield.

Then you'll need to remove the other part where the wiper motor and the mechanism that moves the blades. It will take about 12 bolts to get it out.

Once you've finally removed both parts, you can remove the smaller blower duct near the center of the engine compartment and you will see something like this:

http://img685.imageshack.us/img685/2897/img00150201106260933.th.jpg (http://imageshack.us/photo/my-images/685/img00150201106260933.jpg/)

And this is where the blower duct is attached to:

http://img215.imageshack.us/img215/1015/img00151201106260933.th.jpg (http://imageshack.us/photo/my-images/215/img00151201106260933.jpg/)

The next part is to disconnect the VSS harness, you can locate it by looking form the drivers side straight under the coil pack, you can see it in the picture (near the center of it) below the blue and white dots:

http://img98.imageshack.us/img98/4860/img00163201106260951.th.jpg (http://imageshack.us/photo/my-images/98/img00163201106260951.jpg/)

In the next picture you will see the spot where you'll need to use to get to the VSS (from this place it is located right between the rear exhaust manifold and the engine block). Route your hand through the square you can see at the center of the image, right between the rubber hoses and the plastic wiring tubing. You can choose to remove the vacuum hoses for the brake booster and the EVAP Regulator from the intake manifold to have some more free space:

http://img232.imageshack.us/img232/1719/img00167201106260952.th.jpg (http://imageshack.us/photo/my-images/232/img00167201106260952.jpg/)

Now that you know the route and have enough space, you can take your hand under there, access through the driver's side of the exhaust manifold (don't try to use the other openings as your hand won't fit), and feel the rectangular heat shield on top of the VSS, in the next picture you can see it at the upper left (it's not a very good picture but I posted it just to give you an idea):

http://img41.imageshack.us/img41/2959/img00169201106260954.th.jpg (http://imageshack.us/photo/my-images/41/img00169201106260954.jpg/)

This video will show you (kind of) the route your hand needs to follow to get there. In it you will see the VSS and the heat shield for the first time:

http://youtu.be/JTmgpmvDNJM

TIP: It is easier to reach the VSS when you're sitting on the metallic part on top of the radiator and the battery. It doesn't matters how tall you are (I'm 6'2") it's still hard to reach there.

Use an 8mm socket to remove the bolt (located at the opposite side of the wiring) that holds both the shield and VSS in place. The best way to do it is using a ratchet, a long extension and universal joint. Insert it thorugh one of the openings in the exhaust manifold and use your hand to put the socket on the bolt. It depends on each person but I found it easier to use the ratchet on ly to loosen the bolt and then getting it out by hand. Make sure you don't loose it!.

Use a rag or compressed air to blow as much as you can around the VSS to get rid of as much dust as you can. You can finally take the VSS out, it is coated with some transmission fluid so it might be slippery. If you don't have the replacement already make sure you cover the hole with a rag to prevent any dust from entering the transmission.

In the next video you'll see the VSS with the shield removed and ready to be taken out.

http://youtu.be/CIndRLvp97w

Install new VSS and tighten the bolt to 89 lb-in, 7 lb-ft or 10 Nm; any measuring units you want to use.

So that's pretty much it. Assembly is the reverse of the removal procedure, make sure you put everything back together the right way, tighten those bolts, reconnect the battery terminal and GET THAT THING TO BURN SOME FUEL!

Any doubts, comments, etc. feel free to post them here or send me a private message.

Greetings from Mexico!

Oscar.

wiswind
06-27-2011, 08:45 PM
I made this a sticky thread.
Feel free to add any notes that may help others with the VSS replacement process.

Windstartled
04-15-2013, 08:39 PM
Thanks again olopezm, I had done it from below myself. Using gravity as your ally, uh? Now that is pretty smart. This is no joke, doing it from below is the worst approach one can take.

Just want to add a few words of caution here. This is a pretty big job, blind and messy. So before anyone engages into it if they have a code for VSS failure AND front ABS sensor at the same time, or ABS light is on, address the ABS issue first and it might just clear the VSS code. That's because the VSS obtains actual speed data from both front ABS sensors, as does the ABS system. These two small, cheap wheel speed sensors are the most important data collectors on the whole vehicle. When one fails, if you're doing 50 the computer thinks you're going 25 and manages the transmission accordingly. It's a rough ride, and a costly one in fuel and systems wear.

olopezm
04-15-2013, 08:59 PM
No problem! It's good to know that it has helped some people in one way or another.

I decided to find a way to replace it without doing it from below and specially without removing the cats; I was quoted with $210 to have it done by a shop, I said Hell NO!, the price of the new sensor was only $75. I started checking diagrams and searching this forum and was when I found it it could be done from above. It might be a long process but I prefer that to dealing with rusted bolts.

Good thought about the ABS problem. It would suck to go through the process of removing the SS only to find out it didn't solve your problem and it could have been an easier fix.

Oscar.

Windstartled
04-16-2013, 05:09 AM
I replaced my VSS because my speedo was only displaying half my actual speed and tranny was acting up as a result, and VSS code was issued. I only done it from below because I had seen a mechanic at the dealership do it like that on a Taurus while I was retrieving my van after the first recall. At that moment it had not occurred to me that the Taurus had a different transmission and a larger engine bay with less clutter underneath, and even a different platform than a '00 Winnie. That only registered once I was in the process of removing the cats. But when I start something, no matter how ill-conceived my approach turns out to be, I stubbornly stick to it. Took me 4 hours... and I still had the code!!! :banghead:

That's when I noticed the ABS light was on... again. It had been on for a while but I didn't think it was a big deal. I was dead wrong. Being already covered in grease and soot I decided I may as well replace that little wheel sensor, at least the day would not be a total disaster. I proceeded a and lo and behold, no more VSS code, speedometer back to normal, transmission shifting normally. That's when I decided to investigate what exactly was it that those ABS sensors were meant for other than braking, and found that they are properly called wheel speed sensors. From there it doesn't take a genius to figure that a lot of stuff depends on them working properly. Since then I keep spare ones in the vehicle.

But since then I am also a bit confused: what is the VSS for anyway? :p

BTW I believe starting in '01 wheel speed sensors were moved to the rear wheels, which would make sense for accurate data even in icy conditions when front wheels may skid-spin.

olopezm
04-16-2013, 07:12 PM
You're right, my speedometer also jumps from time to time at highway speed; I used to think that after replacing the VSS the problem would go away but it didn't. Later I found out that the ABS sensors are OK but one of the tone rings on the axles is a bit chewed and that's what causes the speedometer to jump; it also causes the ABS pump to kick from time to time at low speeds and stops as soon as I stop or slow down.

In my case, the code for the VSS showed up and the transmission was acting real funny; it was like it wanted to shift to third gear before actually going to 2nd or it would upshift at the same time it would downshift... LOL You get the idea! It goes into limp mode and PCM commands full pressure to the EPC.

From the workshop manual, the VSS is used by the PCM to control fuel injection, ignition timing, transmission shift and TCC scheduling.

Oscar.

Windstartled
04-19-2013, 01:12 PM
From the workshop manual, the VSS is used by the PCM to control fuel injection, ignition timing, transmission shift and TCC scheduling.

Imho they should call it something else because it's confusing to many people who think the VSS is to blame for speedometer issues when in fact these are usually caused by ABS sensors, which are the actual speed sensors. VSS does not "sense" the speed, it just reads it from the ABS sensors. If I understand correctly what it senses is transmission speed.

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