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Discussion Starter #1
i recently purchased a 1996 F350 with the 7.3L Powerstroke (Auto) and im having tranny issues. The previous owner used the truck and was working perfectly fine until he parked her for over a year without being driven and now im experiencing the below problems. The PCM has a 4 Posisiton Bully dog chip in it but that did not affect the transmission at all while the previous owner was using it.

1.Speedometer Does not work,nor the odometer.
2.O/D light is constantly blinking
3. When you put the car in gear and drive out she revs almost up to 3K RPMS and shifts had into gear.

I live in the Cayman Islands and there are not many shops here that know what they are doing with these engines.

Can someone help me out here please? i really would hate to have to purchase a new tranny...:frown:

Thanks!!
 

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1996 has a speed sensor, your speed sensor (VSS) is not talking to the computer, so the truck does not know it is moving
Your flashing OD light usually means there is a computer code
I suspect you get the code P0500 = no signal from VSS

You may simply need to fix your vehicle speed sensor
in 1996 it is still gear driven off a little gear in the tailhousing of the trans (or transfer case) the plastic gear can wear out and or the speed sensor itself just quits working
Your trans is controlled by the computer, if the computer does not know the truck is moving it will go into whats called "limp mode" and you get a flashing OD light. Limp mode is designed to get you just to the nearest dealer. The trans is running at full line pressure = HARSH shifts
You need to get this fixed

1996 powerstroke VSS:
 

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^ That's actually incorrect. That one is for the older model trucks.
Should look like this.

On the top of the rear diff.

Another possibility is a blown fuse.

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Ah crap! In 1996?? Good to know
in 1996 Rangers, Explorers they still use the gear driven VSS until 98!! the rear axle VSS was only for ABS brakes
MY BAD!

Okay so forget about the plastic drive gear and all that, your VSS is in the rear axle ONLY
It is a hall effect style sensor with a tone ring, I would pull yours and inspect it and the wiring to it. They do go bad and are pretty cheap to replace
Often times the issue is in the wiring going to the sensor or the tone ring inside the diff gets mucked up, or both.

<------------------- still learning diesels!! take me to school!
 

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Discussion Starter #5
Thanks guys! suprisingly the store down here has the part in stock, they told me they have (2) VSS one on the transmission and one on the rear axle......anyways will pull out rear axle sensor today and check it out. will keep you posted!

Thanks again!
 

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Starting with the obs pickups is when they went to the tone ring in the rear.


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Discussion Starter #8
Good Morning Guys, sorry i took soo long to update you all but we had a few days of rain here on grand cayman.

Soo i changed the sensor on the rear diff and my speedometer & odometer still do not work & tranny still acting up, i checked the fuses they are all fine. Anymore advise?

Thanks!!
 

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Find out why the light ain't working.
The trans is on the same fuse circuit, iirc.

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It's most likely NOT the VSS. The VSS does not "talk to the computer". The VSS send a signal to the PSOM (programmable speedometer-odometer module - control module for the speedo/odo on the cluster). The PSOM translates that to a digital signal to the PCM. The PCM then uses that signal to control the transmission.

But if your odometer is not working, that is, if it's not even displaying a number, then the fault is more likely in the PSOM, or the connection to it, or the fuse that energizes it. I don't have the fuse diagram handy, but the assignment should be in your owner's manual. Also check the connection behind the cluster.
 

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Discussion Starter #15
Hi Guys!

Sorry for the late response but i ended up buying a 2nd hand speedometer from eBay and installed it about an hour ago...truck shifting like a cadillac but i noticed the speedometer needle is bouncing.....i did replace the sensor a few weeks ago with a new one from NAPA...should i put back in my old sensor??
 
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