Speedo /Odometer gone Tranny in limp mode

[chicken bones]

So I lost my speedo & odometer, the overdrive button is flashing.The Transmission in limp mode.I have checked all the fuses , going to change out the VSS on diff. Do our trucks have a out put transmission speed sensor? I bought a after market VSS but does not seem to fit right,going to Ford next.What should I check aside from wire shorts to VSS ? What is the most common fix for these issues.Thanks.

 

[79jasper]

Need to know the specs on your truck.

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[chicken bones]

1994 F 250 4x4 extended Cab IDI 7.3 Factory Turbo Diesel, Automatic with 4/10 rear end.380000km.I bought it new.

 

[79jasper]

For your year the only vss is in the rear end.
Is your interior dome light working?

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[chicken bones]

Yes,dome light works, all gauge lights work as well.

 

[FORDF250HDXLT]

did you notice there are 2 fuses for the speedo? ones for memory.does the odo show the numbers? everything seems to work but just the speedo doesn't move at all?
try tapping the dash and see if it makes it work a little.if so,it could be bad solder joints on the psom.

http://www.harleyhummerclub.org/PSOM/index.html

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[chicken bones]

The odometer shows nothing,speedo does'nt move.I bought a VSS from ford today, - 8 deg outside and dark when I get home ,but hope to try this real soon.Also notice there is a power control module relay, could it be a relay ? If not I shall look for PSOM,not very good with electrical,repairing it I dont think is an option for me .

 

[FORDF250HDXLT]

the vss isn't your issue.your psom isn't getting power.the vss doesn't supply power to it,just a signal to read to make the needle move and send to the trans control unit.

you skipped my question about the 2 fuses.

far out.i even found ya a video to make it easy peasy Christmas squeezy.

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[chicken bones]

OK I double checked and replaced fuses, and replace them just in case,also installed new VSS still nothing good to report. No Odometer/ Speedo OD starts flashing OFF after first gear shift.Great videos by the way,thanks for you help. I suppose the next step is replace the PSOM?

 

[FORDF250HDXLT]

if theres power going to it but it's still not displaying anything,that's where id head next.

yeah,the trans will be lost without the vehicle speed info.

 

[chicken bones]

I have not check wiring to VSS may have broken or short there ? Or the tone ring in the Diff? I change the bulbs in my gauge cluster once, maybe my PSOM could be repaired ?

 

[chicken bones]

Phone about 10 wreckers today , no one has a gauge cluster/ PSOM for my Truck.Lots of gas trucks, they tell me I can only use one out of the Diesel IDI 7.3 ? Ford has discontinued, keep looking i guess.Good thing it's not my only means of transportation.

 

[FORDF250HDXLT]

all PSOM's are alike.there are no gas/diesel versions.so you can just grab one out of an f150.
there are repair service options as well if you don't want to attempt it.example;
http://clusterfix.net/product/1992-1997-ford-trucks-vans-and-broncos-psom-style-gauges/

 

[chicken bones]

That is great news,they all seem to say it needed to be a Diesel unit to communicate properly.I think i shall inspected all my wiring,grounds,clean up all plugs before pulling the cluster.I wish i could be sure this is my problem, the VSS was not. Thanks for all your help,I like the idea of having mine repaired,at least you know its going to work, your gambling with a wrecker unit.