01 ranger, 3.0, auto trans, 80,000 miles. On level ground, freeway, speed 75 mph (air not on) constant speed . . from time to time for no reason the tranny will drop out of o.d., engine speed revs up then . . a moment later it goes back in o.d. for no reason. Any ideas ?

 

Are you sure it is going in and out of OD? It could be staying in OD and the torque converter will be locking up/unlocking, which would feel like it's coming in and out of OD. Best way to tell is when it does do this, hit the button to take OD off and see if it downshifts and rev higher.

If I remember correctly, these transmissions unlock the converter if that transmission gets warm. Unlocking the torque converter will speed up the pump in the transmission, allowing it to pump more fluid, trying to cool it down.

 

hmmmm didnt know a torque converter would do that. You could be right . . why would it heat up ? fluid full and clean, no abnormal load on truck, I was hoping a sensor like the vss or ? now im real woried . . . bad converter? why to converters lock up?

 

I wouldn't be concerened entirely yet. Somewhere in the transmission (probably in the solenoid body) is a TOT (Trans Oil Temp) sensor. It could be bad.

Converters lock up to decrease engine speed but enable maximum torque to the gears in the transmission. Basically, it's like having an additional gear sometimes.

If your converter locks up and unlocks, than apparrently it's good! Something is telling it to unlock/lockup, we just need to find out what it is. Do you have a check engine light? Pull the codes and see if there is any, reguardless if the light is on or not.

By the way, the converter is controlled by the PCM, which gets readings from several sensors to determine when to lockup or unlock.

 

CEL is not on but I have a code reader, tomorrow Ill look to see if anything shows up and Ill check that overdrive on/off issue you suggested. Ill also see if the Hanes books tell me anything about tranny type sensors .

 

I thought unlocking the TC made for MORE heat? Or is that just when towing? I read that somewhere else on here.

RP
Zach

 

Letting off the gas momentarily or touching the brake will disengage the TC w/o causing a downshift.

 

If you are driving in hilly terrain, it'll shift out more often too & if you're trying to run/maintain 75 mph with the 3slow in hilly terrain, it'll surely do it.

How does it behave on level ground, doing 75???? If it doesn't do it, I'd suggest it might be the terrain & speed you were trying to maintain.

If it still downshifts on level ground, then I'd suspect something else.

Seeing as how the radiator & tranny cooler, (if you have one) is up front, check both for obstructions, say from bugs, or maybe a piece of plastic, or paper, or mud clogging their cooling fins, that would cause the tranny fluid to run hotter than normal.

If that checks out ok, then as has been suggested, pull the codes & see if any good clues turn up & post all you find.

BTW, did this begin slowly over time, or suddenly after some event????

Just some more thoughts for consideration.

 

PawPaw, regarding question: "begin slowly or sudden" ans: trucks new to me so I dont know. Question : "terrain" ans: level ground, checked codes got "System Pass: No Faults Detected"

 

OK, well then are you having any problems with the cruise control dropping out when cruising on level ground????

Or maybe the speedodometer acting up, jumping around a little, or a little unsteady, or the tranny misbehaving during shifting, or the ABS light flickering on & off, or having it feel like the ABS is trying to activate itself, when braking from high speed, if so maybe the speed sensor atop the rear differential housing would be a good suspect.

Are the AC condensor, radiator & tranny cooler fins clean & clear, so you have good, unobstructed air flow over & through them????

Is your scan tool able to read Ford drive train controller trouble codes????

 

No other symtoms. code reader is a Actron cp9145 which does read powertrain. Ill check cc and get back

 

When you hook up your scantool, see if you can monitor the tranny fluid temp sensors output, that handyman was referring to.

If so, drive it 15 miles or so, to warm it up good & see what the sensor reports the temperature as, while your monitoring other things & witing for it to drop out of OD.

When it does, do the capture thing, so the scan tool will store all the parameters it's monitoring when it acts out. Then you can recall them for review after the drive.

Hopefully you'll get a meaningful code!!!!

 

HI; I have have the same problem with a 93 Aerostar 3.0. Below 42MPH Normal above 52 Normal. At 45 the converter locks up than unlocks. Over and over again. It makes no differance if the Engine or trany are hot or cold. 160000 miles never a glitch great Van. Fluid is red. Above 52 I can down shift normal. At 90 it pures like a kitten.
All this time it has worked great 3 weeks ago just like u pop a switch.
Topgo Been around along time but I don't want to tear into the Transmission if the L500 super cushion is slipping in the Radio.

PS only codes is u guested it "111"

 

I had the same problem in my 1987 full size bronc i ende up taking out my catalytic converters that were clogged! I wasnt expecting to fix the fact that my tranny was hunting around for gears. But after i got the plugged cats off it will now hold overdrive even on hills and has quite noticeably more power. It might be something to consider! He runs quite a bit cooler too!