Trasmission Downshifts Around 65

[MOORE1980]

When Driving Around 60 To 65 Miles Per Hour My Transmission Downshifts. If I Let Off The Gas It Will Shift Back Into Overdrive.it Has Been Doing This For A Couple Of Days Now But Not Everytime.this Morning I Drove About 2 Miles And When I Started Off At A Stop Sign It Shifted From High Back To Low. Any Suggestions As What To Check??? PS IT IS A 1995 F150 5.0L 4R70 TRANSMISSION NO CODES OR FLASHING LIGHTS

[projectSHO89]

Welcome aboard.

We aren't psychic, you have to give us enough info to work on. Year, engine, transmission, driveline, etc...

The 95 might have any one of three different automatic transmissions from the factory. Look on your door or doorjam label and look at the TRANS code.

G=C6
U=4R70
E=E40D

Let us know which transmission you have.

Do you have any CEL or OVERDRIVE lights on or flashing?

Steve

[stopper]

He stated in his post that it was a 4r70w and there were no flashing lights or codes.

I would say that TPS sensor is out of whack or the downshift cable is out of whack. I don't think you need a rebuild.

[36fan]

Check the alternator

I know it sounds crazy; however, the OD is elctronically controlled. I've seen a few posts and heard some stories about these trucks doing crazy stuff w/ OD, and it turns out to be early an early indicator the alternator is going out. I'm sure you can do a search to find out more info regarding this than I can provide.

[casey_1]

Originally Posted by 36fan

the OD is elctronically controlled.

Not just the OD, the entire transmission is electrically controlled.

I'll bet the problem is the Transmission Range Sensor (TRS.) It's on the driver's side of the transmission where the shifter cable attaches. It's the part with the wiring harness plugged in. When it starts to fail it sends a signal to the computer to downshif the trans.

[projectSHO89]

Originally Posted by stopper

He stated in his post that it was a 4r70w and there were no flashing lights or codes.

I would say that TPS sensor is out of whack or the downshift cable is out of whack. I don't think you need a rebuild.

Uh, notice the timestamps on the posts and the edit....

No downshift cable....

The TR and TPS sensors are possibilities. You can either load up the shotgun and start shooting and see if you get lucky, or you can follw a logical diagnostic process and increase the odds that you'l get it right much sooner.

Start by running the PCM Quick Test including the KOER portion of the test. This test provides a baseline, even if no faults are noted, of what is working and what may not be working. Instructions maight be around here somewhere, otherwise they're at www.fordfuelinjection.com Only piece of test equipment needed is a paper clip, pencil, and paper and an operational CEL.

Once that is completed, a transmission drive cycle test should be performed. Don't have it on this computer, will post it if needed when I gat a chance to get on the computer on which I have it stored.

Steve