1995 E350 7.3 DI turbo turbo

Instrument cluster looses signal from transmission zero to thirty.
The gentler you are with throttle off the line, the more it hunts for gear.
The speedometer will not read below 20-30 MPH, and frequently bounces 0-30 MPH.

Over 30 there seems to be no issue.



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Might be your VSS on the rear axle.

 

Thanks, this gives me direction..
My ABS light is on all the time.
I am searching other threads, and that seems to be related.
If this is those freaking squirrels chewing wires again!!!

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Look at the wiring to the VSS ,it can also be covered with shavings , pull it & clean it if need be . more than likely you have a PSOM issue .. Get some TPS data if you can too ...

 

I will look at both of these tomorrow AM.
Hope it is simple wire damage or a bad VSS.
Weather: High of 53° F with clouds, afternoon rain dropping to 48° F 15 mph wind.

If it is the PSOM, I hope the dealer has one, this trip is mission critical.

Thankfully a friend (Ford electrical engineer) is coming over in the afternoon to rewire the inverter feed.

https://www.ford-trucks.com/forums/9...t-working.html

https://www.ford-trucks.com/forums/1...placement.html

https://www.ford-trucks.com/forums/1...ed-sensor.html

https://www.ford-trucks.com/forums/1...s-problem.html

 

Bad ground on the rear wiring to the lights and bad wiring / burn't bulbs in the third brake light assembly can also cause these issues ...I also cleaned all the connections from the transmission to the engine and found corrosion in a few connectors as well ....I have had these issues on and off for 3 years.....after replacing 2 sensors , the harness connector, 3 feet of wire and cleaning everything I could see , along with changing the Diff fluid I have drastically improved the situation....

 

Thanks.
My buddy will need to look into this.
Here are pictures of the vehicle, to avoid confusion.






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Ok ...you have an aftermarket body on the back so your wiring is different.... But I would still look into those circiuts...And maybe change the diff fluid to make sure there are no metal particles which could affect the signal from the reluctor gear to the sensor ...Most likely wiring however....Good Luck

 

Thanks for the direction.

The VSS had swelling + scratches on the tip.
The differential MUD was revolting clumped sludge.
I flushed the Super Duty DANA differential, refilled with five quarts of fresh 80-90 gear oil.
Replaced the VSS with a new FORD unit.

The total repair was eight hours.
Differential cover bolts required a three foot breaker bar.
Cleaning the cover bolts used a die on threads and bench wire wheel on the hex head.
Differential cover fill plug was heated with an oxygen acetylene torch + needed a 3/4 drive impact gun for removal, the fill plug was ruined but I was able to clean the cover threads with an NTP pipe tap + replace the plug.
I tapped the cover holes in the axle housing because a previous repair used excess sealer filling them.

The speedometer/shifting is now smooth and stable, as it should be.
Again, my thanks for the direction.

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Glad you got it fixed!