# 99 Ford f350 PSD overdrive/speedometer problem??



## MidAtlantic (Nov 6, 2004)

One of our Fords has has had a problem every now and then the speedometer would stop working and the overdrive light would flash on and off. It wasn't so bad till just recently where it completely went out and only works shortly every now and then. 

I'm guessing its a speed sensor on the transmission or the rear but if you guys have any ideas as to what the problem is and what I need to do to fix it would be great to hear from you.

Thanks,


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## ProEnterprises (Dec 16, 2003)

I had this problem on my truck last year. It was the speed sensor, however, mine quit working all together, and the check engine light was on.


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## Dirt_Werx (Nov 26, 2005)

all i know is watch out for a blinking overdrive, its usually and indication of a serrious problem, have a reputable shop or dealer check it out


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## jbutch83 (Sep 30, 2002)

The overdrive light flashing is an indication that you threw some type of code on the transmission. You need to have the code pulled, to find out what is wrong. 

John


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## ceejay (Dec 13, 2005)

*( speed sensor) in the rear end*

Ahhhh finally something I know all about... I have a F350 ( 1999) and the Overdrive light will flash, the speedometer will not work and the Tach may not work... There is a Speed sensor located in the rear-end. It is on the top drivers side of the rearend... It only costs about 10 bucks at NAPA
I fixed mine myself and Im a girl.... LOL.. Its easy.. It is easiest to get to by crawling under the bumper.. Hope this helps someone.


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## mpflood (Dec 27, 2001)

Been there too, Remove the plastic plug (over the rear end)and inspect.
Sometimes its just not making good contact.

You wouldn't believe how much this works on pinball machines.

P.S. on manual trans fords,the truck will run fine with this plug disconnected.
(un plug and put plastic bags over each end and tape them up)
ofcourse you wont have speedo, but guess what, odometer is dead too 

This wont work on automatics,hence the original post


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## MidAtlantic (Nov 6, 2004)

I figured it was something simple like that..Cause if there was a serious problem when the OD light flashes then I wouldn't have gotten so many miles on it towing real heavy gooseneck trailers with it. It started out about when we hit 30-40,000 miles and was only when towing. Then recently (165,000 miles) after some brake and tire work it really went out.

Transmission shop wants $300-500 to fix the speedometer and said they would rebuild the trans for $2700. I don't see a reason to rebuild a trans that drives out fine and doesn't snap, jerk, pop or make loud sounds. But you know how those repair shops are.


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## douglasl330 (Oct 4, 2005)

Stay very far away from that shop!!!!!!!!!!!!! Good Luck!!!!1


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