Trans wont kick down when in overdrive

[tombombadom]

I did a search for this, but didn't find anything. So I will ask:

On my 96, which if I'm not mistaking has the 4R55E transmission, all seems well except for a couple of things (they don't seem too serious)

Sometimes the shift into overdrive is extremly delayed, like it will hang there in 3rd gear, you almost have to let off the gas to get it to go in. But not every time.

Then once in, if you punch it with out letting off the gas (torque converter locked) it won't kick down. However if you let off the gas (torque converter unlocks) then punch it it will kick down.

Should I be worried or concerned? Transmission seems to shift well otherwise. Has never slipped, or acted any different. Seems consistent weather warm or cold. OD Light has never flashed or done anything erratic.

Some other facts: Truck has about 183K on it, fluid looks good, doesn't smell burnt. Would changing it help, or does this sound like an electronic problem? I don't know alot about transmissions, just enough to be dangerous.

Thanks in advance!

 

[my98nnj]

Check the throttle linkage, make sure your getting the throttle open wide enough to tell the trans to kick down.

 

[OneofMany]

Check the throttle linkage, make sure your getting the throttle open wide enough to tell the trans to kick down.

There is usually a cable between the throttle linkage and the trans... It is adjustable if you look closely at how it connects theres a button to unlock it and move it. move it slowly 1 notch at a time. Maybe mark it. However i dont think it is the issue. I think your problem is the vacuum modulator. 1st check the vacuum line from the vacuum tree at the back of your intake. from the vac.tree it is rubber for maybe 5 in. then metal, then rubber again connecting to the modulator at the trans. Its a round thing behind the cat. One tell tale of it being bad is trans fluid in that line.

 

[tombombadom]

I will check both. It will kick down in any other gear EXCEPT Over drive. I will look it over good, and report what I find.

 

[tombombadom]

I also noted a slight flare in 3rd gear when it goes to lock the converter. Not every time, more so under load. Maybe the problems are related?

 

[4X4 Explorer]

Concur with all above. I would add to change transmission fluid and filter. Be sure to clean pan and wipe any accumulation of grit from magnets. Above issues disappeared from my 96 Explorer after change. Does not hurt to add magnet to inside of pan, Transmissions hate grit/metal filings.

 

[tombombadom]

I have another question, would it be possible that a malfunctioning throttle position sensor could be to blame? Like I said before trans will kick down in any other gear, just not over drive. I do plan on servicing the trans. And also changing some cluster lights (some are burnt out, including the check engine light) which returned a P0121 code I believe. Thoughts?

 

[lighttech]

Tps

I would think that your transmission does not have a kick down cable. I may be wrong on that, but I believe its computer controlled.

The Computer uses TPS (throttle position sensor) in conjunction with MAF (Mass Air Flow Sensor) to calculate when to upshift and downshift. I know in my '95 its that way, and there are tests you can do to check it.

Do you have any check engine light activity ?

 

[albi1cnobi1]

I would think that your transmission does not have a kick down cable. I may be wrong on that, but I believe its computer controlled.

The Computer uses TPS (throttle position sensor) in conjunction with MAF (Mass Air Flow Sensor) to calculate when to upshift and downshift. I know in my '95 its that way, and there are tests you can do to check it.

Do you have any check engine light activity ?

Correct. There is no kick down cable on your tranny. The tranny is controlled by the computer using inputs from various sensors.(TPS,VSS,MAF, and a few others) I would look at your TPS first. There is a test procedure sticky-ed on here somewhere. After that a fluid drain and inspection isn't a bad idea.


OneofMany: However i dont think it is the issue. I think your problem is the vacuum modulator. 1st check the vacuum line from the vacuum tree at the back of your intake. from the vac.tree it is rubber for maybe 5 in. then metal, then rubber again connecting to the modulator at the trans. Its a round thing behind the cat. One tell tale of it being bad is trans fluid in that line.

There is also no vacuum modulator on the 4r55e. It is totally computer controlled.

 

[1992fordgreen]

His Explorer has no kickdown cable. Those were on 1994 and older models. 1995 are electrically controlled trannys.

 

[tombombadom]

I do not have a check engine light on, however I know that the light is burnt out. I just happen to plug it in and get a p0121 code. Makes sense to me, it pry won't kick down since its not getting a signal from the tps. At least it makes sense in my head. I will check the tps. Thank you all for all the information! Much appreciated!

 

[1992fordgreen]

Was it the TPS?

 

[tombombadom]

Yes it was. I don't know of there was just a bad connection or what, but I unhooked it and hooked it back up and now it's working great. Solved all of the shifting problems I was having.

 

[1992fordgreen]

Sounds Kosher! I'm having the same problems and I'm hoping it's my TPS...