2003 Sport Trac 5r55e speedometer signal?

[jdjr131]

How is the speedometer driven in a 2003 sport trac equipped with the 4x4 5r55e? I keep seeing different answers for where the PCM gets the signal, some say an OSS, others say vss in the rear differential or the transfer case (I know this is a model year thing, but the answers I'm finding are confusing me). I manual swapped my truck recently and it seems my speedometer no longer works; I'm assuming the 5r55e had an OSS sensor which the computer relied on for vehicle speed, is this correct? And I'm trying to figure out if I'm wrong and it's related to sensors in my differential or transfer case, or if this is something I may want to reverse engineer a solution for? I'm thinking of using some sort of micro controller and converting velocity via GPS data to a signal the PCM can use. Is this even something that would be possible? Or is there some sort of easy/obvious solution I'm overlooking?

I really don't want to have to look around for the proper extension housing with the OSS hole because I've already done a lot of part sourcing and driving around, doing that in between school and I've started to become tired of it. I'd prefer to find a solution I can work on from my desk

Thanks

 

[410Fortune]

I can tell you

The rear axle vss sensor feeds the 4wabs module under your hood I’m the 2001-2002 trac. Sometime in 2003+ the oss sensor was used mainly. Regardless the following is true:
The 4wabs module still gets the vss signal from the rear axle
In 2003 the pcm performs the “buffering” needed from the oss/vss signal to turn it into the 8000 pulses per
Mile the v6 speedometer/cruise control/ gem module want to see

You can get that speedometer working again by using a dakota digital speedometer interface installing it and calibrating it to emulate the 8000
Pulses per mile the speedo will understand
or
by installing a. GPS enabled speedo interface which does the same thing without programming

When I remove the v6 computers and install v8 into these trucks I get the same problem you are having, no more speedo

Check this out:

Ford Ranger forum

The Premiere Site For Ford Ranger Enthusiasts

ford-rangers.com

And here

Ford Ranger forum

The Premiere Site For Ford Ranger Enthusiasts

ford-rangers.com

There is no 5 speed tailhousing or output shaft with an oss drive sensor as far as I know.

 

[jdjr131]

Oh wow, that was much more information than I was expecting. Thank you very much. So the solution shown is getting a Dakota Digital Speedometer calibration unit to use the signal from the VSS that's being sent to the 4WABS module? Is it basically producing an output that's a fraction of the VSS signal to get it within the range of the 8000 PPM the gem expects? Would I be able to produce such a signal with an Arduino or similar micro controller and tap directly into the signal wires for the GEM to give it the 8000 ppm it wants? Does it require an AC signal or is it really just looking for an on/off sorta thing to determine speed from the frequency? I'm not too well-versed with the electrical side of things, so I'm kinda approaching this problem a little blindly.

But if I want to go the premade GPS speedo interface route, would something like the Dakota GPS-50-2 work?

And I assume I should pickup a wiring diagram so I know what wires go where and do what, where would be the best place to source this?

Thanks.

 

[410Fortune]

Do it exactly as shown in the thread
Yes you can use the gps enabled dakota

You must and I mean must tap into the vss wire where I did just before the abs pump
And the feed must go into the truck where I put it going to the gem speedo etc

I can provide wiring diagrams for 2002 truck I do not have 03

The old ford cable driven vss (1986-1995) was calibrated at 8000 pulses per mile, nothing has changed on the truck side of things. In 96 the cable went away and the speedometer itself was now electric and also needed the 8000ppm so the gem module did the “math” or buffering needed… then later the engine computer did the math…. And it accepted inputs from the iss and oss on the trans… Now When we remove the pcm all of that goes away. So we need to add a module that can take any speed sensor signal (oss or vss) and perform the math needed to send the 8000ppm to the speedometer and body computers

All of our trucks have a vss in the rear axle, all 96-11 rangers, all 96-04 explorers, tracs, etc so that is the sensor I decided to use to run the Dakota. It is important that we tap in where we do so we do not effect the abs brakes

I am sure there are other ways to calculate the 8000ppm from various speed sensors
The Dakota is/was $100 and it is adjustable as you drive so with tire changes etc you can always dial in your mph making the speedo, new pcm, cruise control happy

I have used these now on trucks from the 90’s all the way up to 2005 now, it works awesome in every conversion so I am a big fan of the Dakota.

You can see the input and output settings I used to do the math to reduce the vss signal down to the target 8000 ppm, really simple when it is all said and done

Should work great for your 03 too

 

[410Fortune]

Getting a 2003 sport trac wiring book is a very good idea! It’s funny how we do the conversion first and then get the book later lol eBay is a good source for these often used for under $40’or so I collect all the years I can
I have 02 sport/trac 05 and 07 ranger (02-04 sport trac basically is a ranger)

The vss signal can be calculated using input from any wheel speed sensor front or back or even the oss sensor if you have one… any sensor that rotates 1:1 with the driveshaft or tires (I prefer tires)
The math will just change on the Dakota side

To use the rear axle vss I had to count the teeth on the 8.8 stator gear and figure out how many pulses the vss was generating per mile this got me close enough to get the Dakota to read and then I adjusted the numbers from there to get gps accurate speedo signal

The nice part about using a bit from Dakota is you know it will last, some of these trucks have been on the road for a couple of year now….
Never a hiccup

Just my 02 let us know what you find out or if you need any more info

 

[jdjr131]

If you don't mind, may I see the wiring diagrams for the 02 sport trac please? I think I'll try to compare information from diagram to what is what I can see on the truck itself to see if any of the stuff lines up and go from there. I'm hoping that the sport trac didn't undergo any major electrical changes throughout the first gen run.

And I figured that the 02-04 sport trac is basically a ranger after tearing everything apart; basically all the information I used was for the ranger while doing the manual swap

Thank you

 

[410Fortune]

Page 3 of the 02 sport trac conversion thread actually has the 02 wiring for the vss circuit outlined. I even took pics of my hand drawn circuit diagrams for 679 the vss circuit after it leaves the abs module

When I get a few
Minutes I can take pics from the 02 book for you as well

Yea