overdrive off light flashing.
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overdrive off light flashing.
So I recently bought a 1999 f250 super duty with the 7.3 powerstroke I got a great deal on it and it only has 120,000 miles. When I am driving if I really get on the pedal the overdrive off light flashes then it starts shifting hard, I have read a lot of the threads about it, so I replaced the vss, and it still does it, So I thought maybe it was the tranny, so while in park I accelerated to the floor and it started doing it. as soon as I shut the motor off and restart its fine unless I get on it again,......somebody said it could be a vacuum leak??????Any ideas> thanks
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,704
Likes: 2,625
From: SE Florida
It's not a vacuum leak. There is no vacuum to leak. If you don't get the codes read you won't know how to fix it. The auto parts stores that read codes CANNOT read these codes.
If you don't want to get the codes read the only other way is to change parts until you get lucky. If you want to do it that way I can list all the parts and you buy them. Usually we can find the problem this way in the first $5,000. Sometimes it goes into the second $5,000. Or you could get the codes read and fix it right the first time.
If you don't want to get the codes read the only other way is to change parts until you get lucky. If you want to do it that way I can list all the parts and you buy them. Usually we can find the problem this way in the first $5,000. Sometimes it goes into the second $5,000. Or you could get the codes read and fix it right the first time.
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,704
Likes: 2,625
From: SE Florida
While we are guessing, it could be the turbine speed sensor, the output speed sensor, one of the shift solenoids, the transmission temperature sensor, the transmission range sensor, the vehicle speed sensor, any of the wiring to any of these sensors, the alternator, or a bad ground. I'm sure I missed some, too.
Either replace all of these or ignore all of the stupid guesses and find out what's wrong by reading the codes.
Laughing Gas
Joined: Jul 2010
Posts: 1,025
Likes: 1
From: Clearwater Fl.
Like Mark said, get the codes read. Any other way is a waste of time. When the overdrive on/off switch flashes, it's a transmission code. My truck was doing it a couple of months ago. Mine was showing 503 - vehicle speed sensor intermittent, and 722 - output speed sensor circuit no signal. I had them clear the codes, and so far they have not come back. My truck sits most of the time, so I think that might have had something to do with it. I try to drive it somewhere at least once a week now. If you don't get the codes checked out, you are wasting your time.
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