The VSS should not have any "play" in it. Any movement will cause an erroneous change in the output signal.

 

If the speedometer is bouncing around and the speed control will not keep engaged then the light in the end of the shift stalk would not tell you anything yet.

The light in the end of the shift stalk is turned on and off by the PCM computer. The PSOM is feeding the PCM Computer so if the signal is bad to the PCM Computer then it may also blink the light in the end of the shift stalk.

There have also been cases that the speedometer would bouncing around above a certain speed and the PSOM had to be changed out to fix the problem or so they have posted. But I do not know if the PSOM was draging the voltage lower from the rear VSS (ABS sensor) or not in these cases.

 

And just for grins.........

My 94 had a bouncing speedo problem.

There were a few things happening.

First......I installed an "easy tap a fuse" connector on fuse #8 IIRC (for a camper shell light) that was a little sloppy and the fuse was making intermittant connection in that circuit.
It took me several weeks to find that one !!!!!
Make sure your fuse block (under the dash) is holding your fuses snugly.

Second....... I cleaned up just about every ground I could find that had anything to do with the ground circuits of the cab, computer, and instrument cluster.

Third............. Since I wasn't the origional owner, I found MULTIPLE problems with the wiring connectors in the instrument cluster.
There was a "alarm/disabling device" that was installed and removed incorrectly that affected the ground circuit within the cluster/guages.
It had to do with the door chime ground being removed.

That's just some things that might help you in your quest.

Bob

 

Pulled the diff cover was shocked, was expecting it to be a mess in there. LOTS of dirt between the spider gears cleaned it up with 3 cans of brake cleaner checked the clearance between the VSS and the tone ring was in spec. No chunks missing from the tone gear. No play in carrier bearings, no chunks missing from ring gear or pinion everything was nice and tight even checked runout didn't have any.

Now on the #8 fuse I checked that and they had the trailer brake controller hooked into there so I will be looking into that closely and attempt to repair. Not sure how to so if you could chime in here that would awsome (one of the connecters is bent quite a bit.)

Also on the dash problems, the oil pressure gauge does not work just stays at 0 (truck has good oil pressure)

The kid I bought this from lived on a gravel road (extremely bumpy).

now on the wire I repaired I just tied the wires together and electrical taped them, they did not look copper though. They were a greyish color ( I have trouble telling the difference between colors) thinking I should get a chunk of wire and a soder gun and go back under there and do the splicing properly.

Up to 35mph no real flutter

After 35-50 5 mph flutter

55 - 70 10-15 mph flutter

Cruise just keeps accelerating it works it just doesn't stop accelerating.

Now I am assuming I am going to be pulling the dash tomorrow to have a look see. But what should I be looking for? Besides unplugging the vsom which from what your saying would not be causing the low voltage at the rabs test port.

Now also is there a way to test the wiring to the speed sensor to possibly aid me and narrowing down the problem? There was also some moisture on the harness connector going to the vss. Also going to be looking at the grounds and cleaning them up, I have had issues with grounds before on my taurus and I refuse to replace parts only to find a bad ground.

Sorry guys I have add and keep forgetting to add stuff.

Thanks for your help again guys.

 

If you take the cluster apart and take the PSOM out look for bad caps and loose parts on the board. Re-solder if necessary.

 

I took out the psom today, found few burnt out bulbs one of them being the check engine.

As far as the solder goes I could only find one thing that look slightly off from everything else. And i'm not even sure if its bad going to describe the best I can.

Directly to the left of the SW2 there is a horseshoe type thingy, where that goes into the board closest to the edge.

The connector goes into the board andit looks like there is a small gap around the inside section where the prong connects to the board I cannot describe it....not sure where to go from here.

https://i.imgur.com/vVD1BRQ.jpg


EDIT: This is almost exactly what it looks like http://softsolder.files.wordpress.co...usb-memory.jpg

 

That needs to be re-soldered.

 

Re-sodered the wire no real change at the start of the test drive, no real change for the first mile or so noticed that everytime the speedo bounced the airbag light flashed not sure if connected? twards the end of the drive the speedometer did not seem to be moving near as much as before but still its not fixed...

Also replaced check engine light bulb and the light is on, but my attempts at pulling the code just lead to the error codes :/ not sure how to do it.

 

This link should tell you how to get the codes:
Fuel Injection Technical Library » How To Run a Self-Test
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Alright sorry for late update, spring hit like a time bomb been working a-lot.

PSOM was infact my issue, wanted one with a tach so I bit the bullet and bought one out of a 95, bam issue gone.

I would like to thank you guys for your help, saved me 250 bucks I was quoted at repair shops for this.

now on to the front end and installing my new accumulator body.

But one last question, does anyone know the thread size/pitch of the jam nuts on the ends of the adjustment sleeves? Mine is missing two and everywhere I call they cannot give me a size

ALSO I forgot to say this the transmission is accually a AODE not sure if thats why it shifted normally or not.

 

Did you reprogram them PSOM for your tire size/ VSS tone ring? You may get lucky and get a PSOM with the same settings as your old one if not better verify the speed/ODO to see how far it is off.

Looking at your photo, looks like the capacitor has leaked acid out, its hard to tell from the angle of the photo. I have had that cap leak on my E350 and caused all kinds of tranny shifting and cruse control problems. I replace that cap but the PC board was dammaged from the acid. RIght now I'm getting ready to replace my PSOM but I will be swapping out the EEPROM to the new PSOM I have so I keep the milage and ratios for my vehicle.

I finaly have info about that EEPROM and in time will figure out how to reprogram it.....

 

How about sharing the information with us or email it to me. I would love to see it.
My email address is at the bottom of this post.

 

Well I'm now mad, ole winblows crashed in Dec last year and I lost the info on the eeprom and bunch of other files....... just before I would do the backups of the HDD

Anyway good thing I had good ole notebook paper I used!

The PSOM eeprom appears to be a Microwire varient of the 93Cxx or 93LCxx varity

My notes show pin 1 is either CLOCK or Data
pin 2 is either DATA or CLOCK I only have a O-scope and can't tell the dii

pin 3 is a no connect in the PSOM
pin 4 not sure but the voltage was 1.8V
pin 5 is GND
pin 6 and 7 are no connect
pin 8 is VCC or 5VDC+

I have to relook up the files I once had for programming them. But I don't know how the data is stored in the EEPROM. Haven't gotten that far yet.

I do know the PSOM will write to the EEPROM when it powers down(key off) or every 10 Min it will auto save the data. My E350 Bus started to give crappy MPG(normal 8.6MPG) and I finaly discovered the milage was not being saved in the eeprom at key off!!! Every thing else worked fine. Took 4 months to figure that one out!

I have pulled the EEPROMS out and switched them between the boards with no affect at all. And even tested the PSOM with out a EEPROM, just get the -------- in the odo and the speedo meter bonks out(no ratio data from EEPROM), put EEPROM back in and it works fine.

Once I get back on my feet I'll get more involved(no space or $$$ to do much of anything).


Also by chance does anybody have the PDF copy of the A4LD update book? Or any of the Ford transmission PDF files?

 

https://www.ford-trucks.com/forums/2...-stalling.html

I have a 95 E350 Club wagon and am in need of help. I too have the bouncing speedo. I did the usual quick fix by changing the VSS, with no results. I have now pulled my cluster as it looked to be the fix in the thread above. It seemed to be a problem that was solved by a few people in that thread. I am now concerned that this was not mentioned anywhere in this thread. I cannot find the yellow piece that they are talking about. The thread is old and the main players havent posted since 2005ish. Please post or send me pictures if this has been your solution. Thanks

 

The upper right corner has a yellow diode. That is what they were talking about coming loose.


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