1997 7.3 Towing Issue
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3rd Gear
Joined: Jun 2023
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1997 7.3 Towing Issue
I've got a 1997 F-350 7.3L Diesel with 440k miles. When towing and after the Transmission has come to temperature It shifts from first, through second and into third Immediately... Every time it does this, my Overdrive light begins to blink and I get a P0500 code.
I do have an Edge Insight Programer installed but have never run anything but Stock Mode.
Truck just came out of the shop for this issue and I paid $1,600.00 to replace the rear differential bearings (which were definitely bad). Shop told me that the metallic in the diff. oil from the bad bearings was causing electrical interference with the VSS, which in turn caused the trans to prematurely shift... Towed the day I got the truck out of the shop and immediately had the same issue...
I do have an Edge Insight Programer installed but have never run anything but Stock Mode.
Truck just came out of the shop for this issue and I paid $1,600.00 to replace the rear differential bearings (which were definitely bad). Shop told me that the metallic in the diff. oil from the bad bearings was causing electrical interference with the VSS, which in turn caused the trans to prematurely shift... Towed the day I got the truck out of the shop and immediately had the same issue...
Fleet Mechanic
Joined: Dec 2021
Posts: 1,735
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7.3L engine in this forum is paired with a 10R140 transmission. You wont find much help around here. With that said if youre O/D light is blinking there is a stored code that will aid tremendously in the diagnosis and repair. What is the code that was present when you had the truck repaired and it was determined the VSS was not communicating properly?
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3rd Gear
Joined: Jun 2023
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OverheadCram,
Thank you for the response. Only stored code was A P0500 (VSS). I've replaced the Speed Sensor in the rear diff. three times in the last four years. The last time I replaced it I even replaced the pigtail as well.
Just discovered there may be a Speed Sensor in the trans as well. If there is, not sure my ECU can differentiate between the two....
Thank you for the response. Only stored code was A P0500 (VSS). I've replaced the Speed Sensor in the rear diff. three times in the last four years. The last time I replaced it I even replaced the pigtail as well.
Just discovered there may be a Speed Sensor in the trans as well. If there is, not sure my ECU can differentiate between the two....
Fleet Mechanic
Joined: Dec 2021
Posts: 1,735
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There should be a speed sensor on the very top of the transmission right before the bellhouse. Ultimately id also check wiring and your alternator. A simple short to ground in the wiring or single bad diode in the alternator can cause speed sensor issues from my experience with other Ford models utilizing the TSS and OSS. Unfortunately I dont have much experience with the 98-04 Ford SuperDuty models so cant really answer any more specific on the issue.
Moderator will move your post to the appropriate forum at some point where youll get better help.
Moderator will move your post to the appropriate forum at some point where youll get better help.
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,722
Likes: 2,647
From: SE Florida
It is also possible that there is something going on in the wiring that makes the PCM think that the transfer case is in 4x4L. This can even happen in the two wheel drive truck. One pin in the PCM is grounded when the transfer case is shifted to 4x4L. If the wiring is shorted and that pin gets grounded all of your shifts will happen at very low speeds.
There are no speed sensors on the transmission in a 1997 truck.
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