[TUNINGBYAMG]

HI,
I have a ford f250 XLT 1995, the speedo needle is jumpy after 50 km/h and gets really hectic at over 100km/h (60mph) as speed increases, jumps get higher and higher...

Has anyone encountered this problem and what is possibly causing this... cruise control is also related to this speedo read because it jiggles the truck back and forth once engaged

Any help appreciated

Thanks

 

[action4478]

Check the wiring to the vehicle speed sensor (VSS ) ,on top of the rear diff..Plug could be loose or a break in the wire , or the VSS may be defective ....

 

[MADVAN]

What Rick said.
With

...Rick...
The sensor is in rear of trans? /ubbthreads/images/graemlins/shrug.gif
The one on the axle is for abs. /ubbthreads/images/graemlins/shrug.gif

It gets a little **%$%**ing with year,2wheel 4wheelabs /ubbthreads/images/graemlins/blush.gif
It feels like a monday /ubbthreads/images/graemlins/grin.gif

Bill

 

[action4478]

His VSS is in the trans?.. The last 95 I worked on had the VSS in the diff... Sorry for the mis infomation...( do we have an emicon for sorry? Or oops )....

/ubbthreads/images/graemlins/confused.gif will have to do....

 

[TUNINGBYAMG]

OK,
Thx for the input, yes i have a sensor on the top of the diff, is it normal that when i try to play with the wire it turns around the sensor or is that a sign that sensor is shot?

 

[action4478]

I think what Bill was saying ,is that on your truck , it is only for the ABS,..
The 95 I worked on had a problem with the speedo & engine reving while the cruise control was on,,It had rust under the VSS mounting surface, on the rear diff.. ..On mine , the 97,.. the speedo was bouncing everytime I hit a bump,or drove fast, mine was an almost broken wire,the wire was broken inside the insulation, & would loose contact occasionally... .....

 

[MADVAN]

Rick
This screw up started by ford has been for along time.
Allway's have had problems with wrong parts unless i ask for sensor on rear or trans?
VSS- vehicle speed sensor- trans
OSS- output shaft sensor - trans
RSS- rear axle speed sensor- diff
Check your 97. You will see a sensor on diff and rear of trans.
Disconnect the one off the trans and go drive you will not go far before you plug it back in. You will see what i mean. If you remove the diff sensor you get abs issues.

Bill

 

[action4478]

The problem on mine was the wire leading to it,,The speedo bounced ,,Untill one day the trans wouldn't shift & the speedo quit, & the OD light flashed .... /ubbthreads/images/graemlins/shrug.gif

 

[MADVAN]

From my findings alldata/ford ect some of the info is incorrect/misleading or inconsistent. Gets mixed up, do to 2w/4w/psom/model dep ect.

I will wager a beer on this rick /ubbthreads/images/graemlins/grin.gif
As stated above. Pull the plug on the sensor (trans)/(4x4 t-case).
Trans will not shift nor will you have a speedo and no flashing OD light. Trans will shift at very high rpm then slam a gear.
If you are bored give it a shot. /ubbthreads/images/graemlins/blush.gif

Bill

 

[action4478]

I'm happy to take your word on it ...
My luck ..., if I unplugged it , it would stay that way /ubbthreads/images/graemlins/eek.gif
I have the exact opposite of the midas touch...
Everything I touch turns to S%!t.... /ubbthreads/images/graemlins/biggrin.gif

Oh yeah ,I forgot ,,, I found this in the manualI think its 99 & up

For F-Series, the VSS signal is generated by the Programmable Speedometer/Odometer Module (PSOM). The PSOM generates VSS from a speed sensor on the rear axle.

 

[TUNINGBYAMG]

Ok so if i understand correctly ... the sensor i should be looking out after is the one on the diff on my 95... what does the one onthe tranny and output shaft measure?

And i still didnt get an answer is it normal that the wire on the diff sensor turns about 90 degrees in each direction? Or should it be solidly pointing towards the front or what?

 

[MADVAN]

Introduction of the PSOM is where the confusion started.
Don't remember if early version is from trans or diff. I think PSOM started around 97. (maybe with OBD2). Not shure. PSOM is not in e-series.

Tuning
Pull the clamp off and bend it. Not supposed to move.

Not hyjacking. Just trying to determine if(95) is diff or trans. (sensor/wires). I believe trans.
Pull the wire off the trans or diff sensor and go around the block. Then you will know if no speedo or shift. I would lean on sensor/gear worn or loose.

On Edit--Just rechecked
Seems PSOM started in 92 on the F
Early PSOM has digital odo
I will shoot myself in the foot /ubbthreads/images/graemlins/eek.gif

Bill

 

[masami]

There is a switch on the transfer case for the low range engaged light AND the PCM. When you are in low range and the switch is not adjusted properly, the PCM thinks the truck is in high range and will shift at high range road speeds. Talk about a neck-snapper! /ubbthreads/images/graemlins/eek.gif I know this. When one drops the transfer case, this switch tends to break off. The original switch had no spacer, the replacement did. AND .............

The VSS (rear axle) does supply input for speed and cruise control. They may go bad or may just be dirty. The sensor is magnetic and attracts metal particles. The replacement plastic SD sensor is not an identical replacement for the metal OBS one and may not work but thats all there is now except for the junkyards. The plastic one worked for me though.

 

[MADVAN]

[ QUOTE ]
There is a switch on the transfer case for the low range engaged light AND the PCM. When you are in low range and the switch is not adjusted properly, the PCM thinks the truck is in high range and will shift at high range road speeds. Talk about a neck-snapper! /ubbthreads/images/graemlins/eek.gif I know this. When one drops the transfer case, this switch tends to break off. The original switch had no spacer, the replacement did. AND .............

[/ QUOTE ]

Correct. Its on the front drivers side T-case.
Will also add had a defective switch one time that was stuck in the PCM low range shift mapp while in high. Had super lightning fast shifts till TC locked and motor stalled. All would happen by 10mph.

[ QUOTE ]

The VSS (rear axle) does supply input for speed and cruise control. They may go bad or may just be dirty. The sensor is magnetic and attracts metal particles. The replacement plastic SD sensor is not an identical replacement for the metal OBS one and may not work but thats all there is now except for the junkyards. The plastic one worked for me though.

[/ QUOTE ]

With PSOM.

Non PSOM is on rear of T-case (driverside rear).
His is on the diff, if the F-95 has PSOM which now i believe it does.

You guy's with the f-series have not had above stated issues due do i have now found its a E-series model and year dependant issue. The F data is good its the e data thats not correct. Most of issues are from 2/4w/PSOM non PSOM. Then throw 4x4 conversions into the mix.

Rick
Could of been a cold one on me.
Bill

 

[action4478]

[ QUOTE ]
Rick
Could of been a cold one on me.
Bill


[/ QUOTE ] I was sure "mine " didn't have the Part on the T case,( i I looked last year when I needed the VSS) my parts guy at ford wasn't sure either ,so he had me look.

I couldn't vouch for the 95 , so I was ok to watch this play out, not having much experience in this area. The 95 I worked on, was a 150 gasser,,

I was thinking about the cold one though...