Mechanics

VAN

1995 Ford Windstar • 6 cylinder FWD Automatic • 178,000 miles

I have a 1995 ford windstar van with the 3.8 motor, here goes my question and sorry for the long message, I have a problem with my transmission and there is a engine light on, I borrowed a scanner from a local mechanic shop and scanned the van and a code came up PO500-vehicle speed sensor malfunction, well anyways I went to the local oreillys part store and ordered a sensor but I believe the sensor they ordered is not the one I need, I jacked the vehicle up and removed the drivers tire and where the drivers axle is theres a sensor with a magnet, I checked the voltage there and its within specs, well this is the sensor they ordered and said that it is the vehicle speed sensor-input speed sensor, I have been searching online about the vehicle speed sensor and would other info I gathered was there is a vehicle speed sensor above the passengers axle under the exhaust and the speedometer cable hooks to this sensor, is the sensor that the speedometer cable hooks too- is this the vehicle speed sensor too, well anyways the transmission is not slipping or******** when driving but when you come to a stop sign to slow down it shifts a little bit down hard and then cuts off but cranks back up with no problem, the speedometer works so does that mean the vehicle speed sensors are good even though the diagnostic scanner said bad vehicle speed sensor malfunction, please help me with some advice, this is my wifes van and I dont have the funds to pay a ford dealership 400 to 1000 bucks to fix this problem, I really hate to crush this van because the motor runs excellent and does not cut off till the downshifting hard happens when slowing down to a stop sign, it shifts like hard twice, kinda like a small********, if you could please send me a picture of the vehicle speed sensor, well the ford place said it sounds like I have a bad turbine vehicle speed sensor but the parts storee have no listing for a turbine vehicle speed sensor, the parts store said they have a vehicle speed sensor and its all confusing when two different places tell you something different so I figure you should know and guide ne in the right direction
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Charles Allen Bagwell
March 15, 2011.




I hate to say this but these trannies are prone to problems far more serious. Like 1 day it works and the next it dont. You may want to part with it while it works.


Tiny
Fixitmr
Mar 15, 2011.
Well I hear thats true but online it says the vehicle speed sensor will cause it to downshift when coming to a stop sign, its had a rebuilt transmission put in it, so you think replacing the vehicle speed sensor is a waste of time, its 27 bucks at oreillys auto parts


I'll try to get you started on the road to sanity but hopefully some smart people will add some comments. I'm pretty sure what you have is a copy of the computer-controlled transmission Chrysler came out with in 1989. I know GM wanted to buy the rights to build it but they developed their own design as did Ford I was told. Both had just as much trouble with their early models as Chrysler did. You should find there is no speedometer cable. There are two speed sensors. One is the input speed sensor which could be called the turbine speed sensor. It measures engine crankshaft speed. The turbine is part of the torque converter which is bolted to the crankshaft. The second one is the output speed sensor. It measures half shaft speed. The Transmission Computer knows how fast the axle should be turning compared to how fast the crankshaft is turning based on which gear it's in. The computer has tire size and final drive gear ratio programmed in so it can calculate road speed. That information is sent to the Body Computer, then to the instrument cluster which is another computer module. Yup, three computers involved in running the speedometer that worked really well with a cable for a hundred years.

With Chrysler's transmission, the computer watches how much fluid it takes to apply each clutch pack. In older hydraulically-controlled transmissions, as wear took place, the shifts became sloppy or sluggish but you had a good year of warning that a rebuild would be needed soon. With these computer-controlled transmissions the computer will "learn" to apply the next gear, (third gear for example), then wait a little longer before it releases second gear. That increased overlap creates a nice solid shift, ... Until the day it can't update enough and slippage occurs. That's when it goes to some fail-safe mode. Chrysler calls that "limp-in" where it stays in second gear so you can drive slowly to a repair shop without needing a tow truck. An experienced transmission mechanic can tell how much wear has taken place in those clutch packs by reading the "clutch volume index" on the scanner. That is a set of four numbers corresponding to the number of ccs of fluid it takes to apply each clutch. I don't know what Ford's fail-safe default is but if it is anything like Chrysler's there are some generalizations you can make. If it goes to that condition as soon as you shift into reverse or drive before you even start to move, it is going to be sensor-related. If the problem appears during or right after a shift, usually an up-shift, it is likely to be caused by slippage in a clutch pack.


Caradiodoc
Mar 15, 2011.
S'cuse me for but ting in to your conversation. I typed too long to just delete all that good stuff!

Carry on.


Caradiodoc
Mar 15, 2011.
Well all that you typed hasnt helped me any, my transmission isnt sleeping driving down the road and its not upshifting. If your driving it normal it does shifting great, when you slow down to maybe 30 miles per hour it downshifts twice like the converter is locking and the engine light comes on and the van cuts off but will crank right back up, if yu clear the code the downshifting doesnt occur till the check engine light comes on, please read the question throughly, the fluid is full and isnt burnt and also the transmission has been rebuilt, my van is not a chrylser


No need for an attitude. The Ford system is based on the Chrysler design and most people appreciate knowing how they work. It makes figuring out how to diagnose it easier. If my story didn't help, just don't use it. I would delete it if I could.


Caradiodoc
Mar 15, 2011.
I didnt have a attitude, I was stating what was going on with the transmission, yeah I know the ford system is based on the chrysler design, im just wanting to fix the van cause my wife is nagging about it, I was hoping someone on here has had problems with there vehicle speed sensors, I guess the nice van will be a sardine can, I have a 96 ford taurus and the sensors are good in it, well online and when yu put the model numbers the sensors on the 96 taurus and the 95 windstar have the same numbers, oh yeah another thing I found on the van is it has a axod trans, did the 95 windstars come with a axod because online it says it came with a ax4s


To mr caradiodoc, I would like to appologize to you if I seemed like I had a attitude, well anyways im going to post two pics and could you are someone tell me which is the speed control sensor
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Online at oreillys auto parts its saying this is the speed control sensor, any help would be helpful


Online at orillys its saying this is the automatic transmission speed sensor, any help would be helpful



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