O/D OFF light keeps flashing (99 Sable)

[JimLev]

I was on the highway doing about 75 and then got off onto a country road doing about 40 MPH. The O/D OFF light started to flash on and off, but the car drove and shifted fine. (it did shift into O/D)
I had to stop at a store and when I restarted the car the light was off for the rest of the way home (15 miles). I called the dealer (svc dept) and he said he didn't have a clue, didn't know anything about the light flashing. Got the usual, "if it does it again, bring it in".
There are no OBDII codes, the Sable manual and Hayes manual don't mention the flashing light, but it must have been flashing for some reason.
The tranny is full, but I am thinking that I should get the filter and fluid changed, but this probably isn't the problem. (car has 58K on it)
Any help would be appreciated.
Thanks in advance.
Jim L.

[fxcarden]

Hmm....I just had the same thing happen to me this morning. Car had trouble shifting out of 1st gear. I pulled over, shut the engine off. Started back up. This time the Check Engine light was on, and now the car would not shift at all out of 1st. Good thing I had just left my house, and was able to limp back. There is no reference to this light at all in the user's manual. With only 22,000 on my car, I hope it isn't the transmission. That would suck.

[JimLev]

If the computer doesn't get a signal from the VSS (Vehicle Speed Sensor) this will make the O/D Off light flash on and off. It also effects the shifting of the tranny. My O/D Off light came on today and I didn't shut the car off, but plugged in my scanner and got the VSS code, P0500.
In my case the VSS seems OK, but I don't have the correct voltage going to it, probably from the computer. I have to check the wiring out from the VSS to the computer first to be sure.

[kurliegirlie]

This started happening to my 99 Sable LS over Easter weekend on a road trip. Nothing seemed worng and it stopped when not in high-speed highway conditions. Started again on same trip on Sunday, May 9, and then smoke and fluid started comingo ut of the back of the car. It's been in the shop over a week now and they tell me today they found metal int hepan from a clutch part failure. My advice to you would be to go get the thing checked out, or at least serviced, now!

[JimLev]

I did a filter and tranny fluid change about 2 weeks ago, just after the O/D Off light started flashing and there was no metal pieces in the pan. The old fluid looked good, but I changed it, put the pan back on, ran the car for 10 miles and emptied the pan again. I figure that I got 3/4 of the total fluid replaced. The VSS is $25 and I will replace that as soon as it comes in (back ordered) on Wednesday.
When I checked out the VSS on Sunday it seemed OK, but it is the cheapest part in the loop and I hope it solves my shifting problems.

[JimLev]

The new VSS (Auto Zone $26) checked out electrically the same as to old OEM one, 215 ohms and put out the same voltage while spinning it.
The only difference I could find was that the new VSS spun easier that the old VSS. That really shouldn't has been an issue as the tranny is turning it and has infintely more turning power than my hand.
After installing it, I took it for a 5 mile test ride, shifted smooth as silk, the cruise now works, and no O/D Off light.
The Haynes manual says I should have had 1.5 volts from the computer to the VSS, but I only had 0.62 volts, maybe the book is wrong??