Ford F150 - blinking overdrive

the [off] light on the end of the shifter lever starts to blink when I get over 20 mph and wont stop blinking.also shifts a little hard from first to second.the speedometer has been jumping and wont stay on one speed.I bought the truck 2 weeks ago,and didnt have the problem with the blinking off light on the shifter,hut the speedo was jumping.was told on here that the sensor on top of the differential controls the shifting,and the speedo,could this be the problem?95 f-150 5.0 302

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just bought this truck for 1800,this is my first ford,so I am trying to learn all I can, to do my own work on it

Yes it could be the VSS sensor but could be other things as well. You can try taking the VSS sensor out and cleaning it off with a rag as it may have debris stuck to it.
Other things it could be:
1. Problems in the rear end (bearings or the sensors gear [tone ring]).
2. Bad wiring under the truck (or in other places and plugs).
3. Bad PSOM.

The blinking overdrive indicator means there is a transmission fault.

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A ford F-150 has heated seats because it is driven often in harsh conditions. Can anyone tell me why a Chevy has a heated bumper?

True but he already knows that, he said it has hard shifting.
But it does not mean that there is something wrong with the transmission and the transmission would not make the speedometer jump.

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Bill
subford@gmail.com
1995 F150 5.0 4R70W
1988 E150 5.0 AOD
1983 F150 5.8 AOD
1982 E350 7.5 C6 Class "C" M.H.
1977 F250 351M 4x4 4 Speed
Any comments I make is for a stock wired truck with no modifications unless noted.

Hard shifts don't necessarily mean there is a trans fault. My 2000 shifts hard but has no fault code, the transmission is just mistreated. However, in his case, I think you are right, the two are related.

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A ford F-150 has heated seats because it is driven often in harsh conditions. Can anyone tell me why a Chevy has a heated bumper?

well I put the new abs[vss] sensor in the differential,and the speed sensor on the side of the tranny,and guess what the speedo is jumping worse than it was with the old sensor[which one I dont know] that was already on there.could the speedometer [on the dash]be bad?.I just spent 40 bucks on two new sensors that were probably good,and still dont have a working speedo.by the way the off light quit blinking when I put the new speed sensor on the side of the transmission...I have no clue...my first ford...here we go!!!@##$$##@

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just bought this truck for 1800,this is my first ford,so I am trying to learn all I can, to do my own work on it

The one the transmission has nothing to do with the speedometer.
As I said above other things it could be:
1. Problems in the rear end (bearings or the sensors gear [tone ring]).
2. Bad wiring under the truck (or in other places and plugs).
3. Bad PSOM.

I did not tell you to buy anything and you did not ask how to preform any tests to find the problem.
I do not know of your ability to work on the truck or what tools you have. I was just giving you the items that would cause the problem as if you took it somewhere to be worked on.

Just discovered my blinking shifter light/non-functioning speedometer and abs light were caused by a bad circuit board that resides behind the speedometer. Sourced a used instrument cluster installed it and all problems are fixed. The transmission functioned normally with the issues which indicted electrical issue.