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Ford truck newb
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10 Posts
Discussion Starter #1
Alright guys I've recently purchased a 94 f350 with the 7.3 idi. The day I got the truck it had the typical vss issues. I've replaced the vss sensor checked the wiring and swapped the speedo only to find my problem had been a bare wire in the pass side rear door.

So I got the wiring all patched up in the door, replaced the #8 fuse that kept popping and the problem with the vss / trans was solved. Sadly the day the trans started shifting right the injection pump went out.

Now I've got a new pump in the truck replaced under warranty luckily. But not my vss problem is back and my trans is shifting like junk again. I've about had it... Is there any way around this vss crap? Can I get a stand alone controller for the e4od? Really running out of idea and getting very sick of dealing with this truck. Please help Tia!
 

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Administrator
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8,630 Posts
you already have a stand alone controller in the truck.
does your tach work? there are only two things that will make the trans go into limp mode, no tach signal , and no VSS signal.

get the trouble codes read, and find out what is wrong.
 

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Stone Crusher
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371 Posts
Set the TPS.
 

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Ford truck newb
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10 Posts
Discussion Starter #5
Yep the vss set up on these trucks is the worst thing I've ever seen. There are multiple things that will make your trans shift badly. If a power window or lock wire gets chafed and touches metal your trans won't work, why would ford have the dome light power mirrors windows and locks all on the same fuse block? Any of those things can cause your trans to shift bad.

But anyways sorry, yes my tach works speedo also works. I've got a new vss sensor from ford in the rear axle. My truck doesn't use the vss in the trans. The only thing I can think of is that my TC or trans is failing. The only symptom I have is flashing OD off light. The trans doesn't shift great either but it's not like it was before when my speedo wasn't working.

I also thought maybe it had something to do with me replacing my speedo with a speedo from a gas truck? Probably super unlikely but you never know. Thanks a lot guys.
 

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Administrator
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8,630 Posts
GET THE CODES READ
WITHOUT DOING THIS, YOU ARE JUST THROWING PARTS AT IT HOPING ONE OF THEM WILL FIX IT.
 

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Ford truck newb
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10 Posts
Discussion Starter #7
This is the second time around. I haven't bought anything to fix the problem since the first time.

I looked under the dash for an obd2 port.. It doesn't have one. I'm assuming that's because it's an obd1 style. I don't have much experience with obd1 so I'm not sure how to pull the trans codes.

I'm going up to my buddy's dealership to replace all my ujoints tonight since I'm able to get it on a lift and be in a heated shop. I know for fact they have a snapon versus scan tool I can use. I'm pretty certain it will read obd1 also but I've never done it. Any suggestions about the process would be greatly appreciated. Thanks again!
 

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Ford truck newb
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10 Posts
Discussion Starter #8
I also had a thought today... If I were to swap my e4od for a five speed would I get rid of my problem? Or does the zf5 use the same vss system? Obviously your shifts wouldn't be a problem since it's a manual trans. Just wondered if it would get me out of the electronic mess.

The reason I sold and no longer want a 24v cummins was because of the wiring and sensors that could leave me stranded. I picked this mechanical diesel set up to get away from all of the above mentioned. If I can put in a five speed and get rid of even more electronics I'd be much happier.
 

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Administrator
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8,630 Posts
EEC-IV port in on the driver side inner fender near the hood hinge.
here is a video that shows what the EEC-IV port looks like and how to read the codes.
 

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Ford truck newb
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10 Posts
Discussion Starter #10
Thank you for the reply. I don't see a video though...
 

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Administrator
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8,630 Posts
oops!! forgot to paste the video link.

and here is another one, a writeup on how to check codes.

Ford OBD Trouble Codes
 

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Terminator Nation
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5,119 Posts
92-97 trucks have a PSOM unit on the back of the speedometer. May want to check out the junk yards for a replacement since its no longer dealer serviced part. Gas and diesel units interchange.
 

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Registered
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6 Posts
I had the same problem. Its your torque converter locking and unlocking look up torque converter mod fore4od ttransmission it allows you to control when its locked or unlocked ive had it on mg truck for 60k miles my trans builds less heat runs arpund 130-160 in the hottest of days the mod is great if you do lots of towing also i lock my torque converter at 25 mph instead of factory 35 mph i know its an old post but figured you mighf want to try it if nothing else worked
 
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