98 Windstar, 3.8L, P0500 Where is this speed sensor thing?


Fordina
09-14-2011, 09:52 PM
The check engine light came on on my 98 Ford Windstar 3.8L and the speedometer started working only occasionally. There did not seem to be in trouble with the transmission shifting that I could notice. I had the code read and it is a P0500. The mechanic said it was the VSS (Vehicle Speed Sensor) that needed replacing. The trouble is I am getting conflicting information about where this thing is located so that I can change it out. Some say it can be accessed by taking off the driver side front wheel and loosening one screw and it pops out of the side of the transmission above the axle. Others are saying that it located toward the passenger side of the transaxle, is extremely hard to reach and that the exhaust needs to be dropped. Are there two sensors here and if so, which one do I need to replace? I actually already replaced the one on the driver's side by taking off the wheel but I bought a used sensor from junk yard. Maybe that is the problem. Anyway, I would appreciate any ideas. Thank you.

trannyman52
09-15-2011, 12:49 AM
speedo sensor is on passenger side on top of transaxle,,,right where axle goes into transaxle,,,that signal also tells computer vans speed,,,,if it doesn't see a signal,,,,translates to van not moving,,,no need to shift!!!,,,some what a bitch to get at ,,,but is possible to change....sensor on driver side is turbine speed sensor,,,tells computer what engine input speed is.......since speedometer is acting funny,,,,problem will be sensor on passenger side,,,,should replace with a new one,,,,can be purchased from auto zone,,,or such,,,not real expensive,,made of plastic and aluminum crimped piece of crap,,,does not fair well in the elements,,,,the misery you will go through to change,,,,,you don't want to do it twice for a used piece of crap !!!!!! easier to remove two screws on cover assy,,,remove cover replace sensor ,,then replace cover,,,sensor is bolted to cover assy

Scrapper
09-18-2011, 11:46 AM
ok go to autozone.com and when you punch your car in and get to part you need go to location and if not there click on diadram it will show you so your at what you want and you will get your understanding on this deal.

good luck......

wiswind
09-18-2011, 08:33 PM
If you have the mechanical speedometer (needle that moves, not a LED digital display) then your 1998 Windstar will have a speedometer CABLE that goes from the speedometer to the Vehicle Speed Sensor (VSS).
There is a point, below the flex hose that goes between the throttle body and the air filter box, that you can disconnect the speedometer cable midway.
This leave 2 to 3 feet of speedometer cable connected to the VSS.
The VSS is on the back side of the transmission, near the passenger side drive axle as mentioned above.
It is located above the forward most catalytic converter, which is what makes this otherwise easy repair hard to do.
It is held in by 1 small bolt.

The VSS has a mechanical part that spins the speedometer cable.
There is also a magnetic pickup part that sends a pulse to the Computer (PCM) for each rotation of the speedometer cable.
This pulse is how the PCM knows how fast the vehicle is moving.

The TSS, Turbine Speed Sensor, that is next to where the driver's side drive shaft comes out of the transmission is actually measuring the speed of the intermediate shaft, the shaft that comes out of the torque converter.

So, from the engine speed (tachometer) the PCM knows the speed going INTO the transmission.
From the Turbine Speed Sensor (TSS), the PCM knows how much slippage there is in the torque conveter.....and the speed going into the "gearing".
Then the Vehicle Speed Sensor gives the PCM the speed going OUT of the transmission.
The PCM needs to "know" all of these values in order to properly control the transmission.

You can have a perfectly working mechanical speedometer and a defective electronic part of the VSS (I have had that happen).
In this case, YOU know how fast you are going, but the PCM does not.

Fordina
09-18-2011, 10:22 PM
Thanks, Everyone! I really appreciate all the info. shared here. I'm going to try to get busy working on this tomorrow.

airman105
08-16-2012, 08:47 PM
If you have the mechanical speedometer (needle that moves, not a LED digital display) then your 1998 Windstar will have a speedometer CABLE that goes from the speedometer to the Vehicle Speed Sensor (VSS).

...The PCM needs to "know" all of these values in order to properly control the transmission.

You can have a perfectly working mechanical speedometer and a defective electronic part of the VSS (I have had that happen).
In this case, YOU know how fast you are going, but the PCM does not.

I also have a 98 Wind, 3.8 (mechanical needle) with speedo issues. Seems opposite of what is described. I have no idea how fast I am going but the transmission works fine. The speedometer seems to work fine until about 40 ish and then once you start going faster the needle drops to 0. It used to work until about 70 ish mph and then start to drop off but it seems to have gotten progressively worse. Now after about 40 ish the needle will drop to 0. Van still drives fine even with the speedo at 0. Any thoughts on this one? Accuracy between 0 and 40 seems to be good as well.

Windstartled
08-16-2012, 10:47 PM
Any thoughts on this one?

If you have no shifting issues the most likely cause of your problem is either the speedo cable (it may be loose or rusted inside) or the instrument cluster itself. The former is not expensive but can be a beotch to install. The cluster is very expensive if purchased new from the dealership but junk yards have plenty of them for less than $50. Being that the cluster is a sheltered part even used ones are usually in excellent condition.

One remark of general interest here, when speedo is weird and there are shifting issues the first part to investigate is not the VSS, but the front ABS sensors, then the cogwheel (part of the front wheel bearing), and then the VSS. ABS sensors are the true speed sensors, VSS gets its data from them. As for the cogwheel, if it is damaged it can cause the ABS sensors to send corrupt data to the VSS. This usually causes shifting and speedo issues. The only fix is to replace the wheel bearing.

airman105
08-19-2012, 08:25 PM
If you have no shifting issues the most likely cause of your problem is either...being that the cluster is a sheltered part even used ones are usually in excellent condition.

...and then the VSS. ABS sensors are the true speed sensors, VSS gets its data from them. As for the cogwheel, if it is damaged it can cause the ABS sensors to send corrupt data to the VSS. This usually causes shifting and speedo issues. The only fix is to replace the wheel bearing.

Thanks for the info. I'll see if I can locate the speedo cable. Maybe it's just loose. :)

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