Transmission speed sensors. | Ford Explorer Forums - Serious Explorations

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Transmission speed sensors.

Elayan

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March 20, 2012
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Year, Model & Trim Level
1998 Ford Explorer
I'm about to replace a 1998 explorer transmission whit a 1996 one, they seem to look pretty much the same but the only difference that I can notice its about the speed sensor, the 98 one is located at the middle of the body and the 96 one is located at the rear part, they are different at all. I have the whole line of cables for the 96 so i was thinking to replace trans and cables all together, may someone make some light about this issue?, I have been running down the road about this transmission problem for about a month and I don't want to make more mistakes.
 



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I can't speak for what system came in what years, but I can tell you that earlier model Fords (mid 90's) were likely to have a VSS sensor (vehicle speed), which probably ran off of a pair of plastic gears, 1 inside the trans and 1 outside.

Later model Fords, typically ones having a digital odometer, often got OSS sensors instead (output shaft sensors). Instead of being plastic-gear driven, the output shaft would have a tone ring on it, and the sensor would read the teeth on this ring as it went around. This sent a signal to the PCM, which looked up the gear ratio and tire size in the computer calibration, determined the vehicle speed from these two inputs, and then sent the speed to the instrument cluster module.

If this is what's going on in your case, the two are not directly compatible. There are some conversion boxes out there that you can buy, which take one signal and convert it into the other. Mustang guys use them a lot when they switch trannies around from different year Mustangs.
 






the 96 trans WILL NOT work in a 98, the 98 programming is different to accomdate the 5th gear, and the speed sensors measure different drums, which will throw everything off. You can use any 97-01 trans from either version of the 4.0
 






Thank you all about your advice.
It happen that I have been working the whole afternoon getting that 96 trans up and its already installed, I keep the 98 set of wires and I replaced that sensor at the axis of the change selector because the 98 has 8 connectors but the 96 just has 6 ( I aligned this sensor to the "neutral" position, by the way).
That other connector, that seem to go to insider sensors, has same # of connections so I keep it like that.
Everything is on place now, I completed the job about 3 hours ago, I was about to add some oil and see what happen.
I have 2 questions right now before I add the oil:
1.- If I get one of them conversion boxes that pontiesteve told me, will make this thing work?
2.- Or, is it going to be a waste of money if I add that oil?.

I got this trans from a salvage explorer that was crashed but the whole thing look well, this was a rebuild one and was even just painted. I even can get the transmission down and sell it to someone that need a 96 one.
I already dismount a transmission 3 times on this very same explorer, I just need something that make my explorer running up again.
 






what about the 3rd sensor? on your 98 i know there was a OD drum speed sensor, and if the 96 had the SOHC it may have as well. If you have a 3rd 2 wire sensor it should work, best i can advise at this point is to add fluid and see what happens. mechanicly speaking the 96 and 98 transmissions were the same except the 96 may not have an OD drum sensor. As long as there are no left over connections there is a decent chance this will work. if there is a sensor there but the connector is different then perhaps swapping sensors will work.
 






Look, I could be wrong but doesn't the '98 use a 5R55E, and the '95 uses a 4R55E? I read on Wikipedia 1997 was the first year the 5 speed automatic was available.
 






officially yes, but late production 96 models could also have the 5r, or somebody could have swapped one in
 






Yes, my 98 have a 3rd sensor and is different of the 96, They are just like pontiesteve already described them, what I did before read what pontiesteve had to say is that I cut those 2 wires and I add the conector from the 96 (It was kind of crazy, I know), that way I keep the 96 speed sensor. Now I'm looking to get one of them conversion boxes, I already look for hem on ebay but nobody seem to know anything about it.
What if i just disconnect that sensor at all?, if that is too ignorant from me then just help me, if you can, to get on of those conversion boxes, please.
 






i have never heard of the conversion box that pontisteve mentioned, but searching some of the mustang forums may do you some good. Does the 96 trans have a 3rd sensor? if so i would pull both and compare them, as you may be able to install the 98 sensor in place of the 96 and have it function. But the trans will not function without that sensor
 






Yes, the 96 also has 3rd sensor, its located at the rear part of the trans instead of the 98 middle part. They don't fit at all, there is no way you just could swap them and either there is no hole on the 96 trans body to install the OD drum 98 sensor. I didn't swap them, I chopped the 98 connector, peel the cables and twisted them to add the 96 connector to those 2 wires that now are connected to the 96 sohc speed sensor, I suppose that is gonna mess with the computer. Today, I'm gonna add some fluid, see what happen and I'll come back to let you know.
 






I added some fluid to the trans, and this is what happened:
1.-I can't believe it but i got my speedometer working, at least i can read my speed at my instruments panel. Seem that I didn't need that conversion box, seem that those 2 different speed sensors weren't too different after all.

2.-Anyway, trany is not working like I wish, Its doing the shift from 1st to 2nd at 32 m/h and 3000 rpm, 2nd to 3rd at 42 m/h and 3000 rpm, 3rd to 4th at 52m/h and 3000 rpm. They feel like pretty long, long shifts.

3.- Trany is not slipping, you can feel the power under your fuel pedal every time, it feel more like a manual transmission.

What's next?, I think I gonna have to replace this 96/4R55E for a really 98/5R55E, Right?
 






yea, unfortunatly that is the only option, any 97-01 trans from either version of the 4.0 will work. You can also recycle the trans fluid you just bought if you are brave enough, just be sure the pan is clean, and filter it as you funnel it into the containers (i would use a coffee filter)
 






What about swapping computers for the newer vehicle instead? If the wiring harness is the same, and if the engine is the same and uses the same injectors and mass airflow sensor, theres a good chance that would work.
 






Like you already noticed I'm a novice, Where is that damn computer?, I have been looking for it but I'm not sure.
 






the computer is in the firewall, under the hood, you want to try the one that matches the 96 transmission, that may or may not work, so the question is weather or not the cost of the computer is worth the 50/50 chance that the 96 pcm will play nice with your 98 sensors. I dont think any of the sensors are different, but i cant say for sure
 






I decided to give my Ford repair CD a look, and see if I could shed some light on the subject of what trannies have what sensors.

The 4R70W trans has the following:
OSS output shaft sensor
DTR Digital Transmission Range (a neutral/park switch basically)
TFT Transmission Fluid Temperature
VSS Vehicle Speed Sensor

From the Ford manual:

The vehicle speed sensor (VSS) is model dependent. Possible sources of vehicle speed input are, anti-lock brake sensor (ABS), a gear-driven vehicle speed sensor (VSS), or the transmission output shaft speed (OSS) sensor. On 4x4 applications with a manual shift transfer case, the transfer case speed sensor is the source of vehicle speed. The VSS signal is either an AC signal whose frequency changes with vehicle speed, or an SCP data message depending on the source. Some vehicles have both. The vehicle speed signal is an input to various vehicle sub-systems such as the powertrain control module (PCM), instrument cluster (speedometer and odometer), speed control systems, etc. The vehicle speed source must be operational to enter output state control mode for diagnostics.

Now, for the 5R55E:

TSS Turbine Shaft Speed (The TSS sensor is mounted internally on the center support.)
OSS Output Shaft Sensor (located at the output shaft ring gear)
DTR Digital Transmission Range
TFT Transmission Fluid Temperature

Ok, now I have a headache. It's too complex to read this stupid CD. It seems in some places, to indicate that the Vehicle Speed Sensor is the rear axle sensor (rear ABS sensor).

In some places, it indicates there is an output shaft sensor, turbine shaft sensor, and an intermediate shaft sensor in the 5r55e tranny. The various shaft speed sensors all tend to control pressure, while the turbine and output shaft sensors affecdt converter lockup also. The OSS seems to be the only one that affects shift schedule.

You need to put the right tranny in that thing. There's a big difference between the 4r70w and the 5r55e. Computers included in that statement.

The computer is located in approximately the middle to middle-right of your firewall. The end of the computer sticks thru the firewall by an inch or two, and the computer calibration code (4 digit alpha-numeric) can be seen on the sticker. The computer is mostly inside the vehicle, but the end of it sticks out into the engine bay, where the harness connectors plug into it.

It is possible to swap computers from say a 4.0 OHV 4r70w combo to a 4.0 OHV 5r55e combo, as long as you switch the computer and the wiring harnesses. Or at least any differences in the wiring need to be converted. Those type jobs are always rough.

The converter box I mentioned is not what's going on here, but FYI Ford Racing sells one called speed cal, and Dallas Mustang sells one as well. I think there may also be a different box that can convert from one type of VSS signal to another. Ford Racing would know.
 






Now I have a headache too.
I'm think the best thing to do is to get that 96 tranny down, try to sell it (because there is nothing wrong on it, its working well), get a 98 tranny, and enjoy my explorer again.

Let me tell you something my original transmission: It blew my radiator pipe twice, I changed the fluid the 1st time, then it started slipping; by the second blow, I didn't care and I keep that emulsion (fluid & water) and SLIPPING STOP!!, that last almost a year then it broke down. I'm wasn't planned to use that trans again ( because all this time with water inside) so I tore it apart, I chopped insider sensor cables, took the VB away. That trans is useless now.
 






Now let me tell you something of what happened next:
I bought a used 98 trans, everything was the same, so I installed it up, regretfully that trans didn't work well, it starter doing everything right, then (after a few miles when you made a stop) D and R were gone, you had to shift to 2nd, then you could come back to D, but no R at all.
I asked to the guy to sell it to me and he told me that maybe the torque converter slip away and fluid pump wasn't working, he asked me to get the trans down back, fill the torque converter with a quarter of fluid, and make sure that TQ doesn't "slip out" again, I did what I was been asked but next time it was even a little bit worse. No D nor R after a few miles again, but if you shift them and then you waited a little moment the traction started slowly. A weird thing was that every time I returned to my driveway and the vehicle got up at he front by like 1 foot (just the usual inclination up every driveway has) then D and R shifted just right, WEIRD!.
I still have that 98 trans. Do you think I could make it work up?, what parts am I going to need to change?.
PS: I forgot to tell you that I flushed out all the water & fluid emulsion from the pipes and radiator before I installed this used 98 trans first time, just in case you wanted to ask me.
 



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Now let me tell you something of what happened next:
I bought a used 98 trans, everything was the same, so I installed it up, regretfully that trans didn't work well, it starter doing everything right, then (after a few miles when you made a stop) D and R were gone, you had to shift to 2nd, then you could come back to D, but no R at all.
I asked to the guy to sell it to me and he told me that maybe the torque converter slip away and fluid pump wasn't working, he asked me to get the trans down back, fill the torque converter with a quarter of fluid, and make sure that TQ doesn't "slip out" again, I did what I was been asked but next time it was even a little bit worse. No D nor R after a few miles again, but if you shift them and then you waited a little moment the traction started slowly. A weird thing was that every time I returned to my driveway and the vehicle got up at he front by like 1 foot (just the usual inclination up every driveway has) then D and R shifted just right, WEIRD!.
I still have that 98 trans. Do you think I could make it work up?, what parts am I going to need to change?.
PS: I forgot to tell you that I flushed out all the water & fluid emulsion from the pipes and radiator before I installed this used 98 trans first time, just in case you wanted to ask me.
pull the pan and verify the filter is still in place, if it is then it sounds like a rebuild is in order
 






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