Transmission doesn't lock in overdrive, HELP!!

[airdrew99]

I need some advice on this. I have a 2000 PSD with the automatic transmission and 4WD. I just recently changed the transmission fluid (including the filter and draining the torque converter). When the outside temperature is around 60*F or lower, the transmission will shift fine until I get to around 55 mph. At that point I'm turning about 2,200 rpm and it won't shift into overdrive (or it won't lock-out). I try adjusting the throttle pedal to get it to shift, but it won't. After about 5-10 minutes of driving, it will shift just fine into overdrive the rest of the day. This occured before and after I changed the fluid. The truck has 160,000 miles on it. Does anyone have any ideas of what is going on? The transmission shifts great other than the problem I described. Thanks in advance for any advice.

Drew

 

[airdrew99]

I forgot to mention: I installed a trans temp gauge on my truck last year. I usually read about 100-125*F just driving around town. I did see around 165*F this past summer while pulling my Mastercraft down the interstate, but it was only for a short time.

 

[Tail_Gunner]

Sounds like the way mine has operated all along.

I think what it is doing is related to tranny fluid temp. It seems like my torque converter doesn't lock-up until after the truck has run a while and the fluid has warmed up a bit. But I typically don't see this sort of thing happen above say 45* or so. The torque converter usually begins locking up within 5 minutes of a cold start.

If you have the ability, hook up an Autoenginuity and get a direct read out of the value the tranny temp sensor is reporting to the PCM. I'd do it before the first start of the day, the temp sensor value should be pretty close to the outside ambiant air temp.

 

[BJS]

TG hit the nail on the head your converter will not lock until the transmission temp according to the temp sensor on the valve body reads that it is 90° IIRC. This is a notable delay when it is cold and I think that's what you're feeling


Once you get the temps up then it's time to check and see if your converter is locking but if the highest temp you've see is 165° when you're towing then you're locking up.

 

[airdrew99]

Tail gunner,
I'm not sure what you are talking about with the autoenginuity (or whatever). I do get the tranny to lock out after about 5 minutes of driving. Is there an adjustment I can make to cure this or is this how Ford designed it to be? Thank you both for replying back so soon.

Drew

 

[Tail_Gunner]

Tail gunner,
I'm not sure what you are talking about with the autoenginuity (or whatever). I do get the tranny to lock out after about 5 minutes of driving. Is there an adjustment I can make to cure this or is this how Ford designed it to be? Thank you both for replying back so soon.

Drew

Autoenginuity is a software and hardware cable package that allows you to do diagnostics & trouble shooting on your truck using your computer. It does everything you could ever need to do without the expense of a mega*****$$$ diagnostic scanner that a lot of dealerships use. Several of us lurking around here have our own AutoEnginuity

One of the functions an AutoEnginuity will do, is a direct data read of all the various temp, pressure and speed sensors on your truck. If for example, your tranny fluid temp sensor is telling the PCM your tranny fluid temp is 0*F but the outside air temp is more like 50* to 60*, I think that would indicate a possible problem.

 

[trackspeeder]

Tail gunner,
I'm not sure what you are talking about with the autoenginuity (or whatever). I do get the tranny to lock out after about 5 minutes of driving. Is there an adjustment I can make to cure this or is this how Ford designed it to be? Thank you both for replying back so soon.

Drew

That is the design of the tranny. You will have no TC lock up until the tranny has warmed up.