I have a 2000 Ranger with a 3.0 and 44R4 automatic transmission that will not shift into overdrive. There are no codes. When I turn the overdrive on and off with the gearshift button the overdrive light goes on and off so I don't think it is a broken wire in the steering column. When I am driving above 45 and turn the overdrive off the RPM drops and I assume that is the torque converter locking in. It will NOT lock in with the overdrive on. All fluid levels are normal. Any help for where to look next would be appreciated.

 

Welcome to the forum

Its a 4R44E

Torque converter should lock on its own above 35mph, computer can lock it earlier depending on throttle position, speed and engine RPMs
Speedometer is working I assume

Computer has a transmission turbine shaft speed sensor(TSS) and it will set codes if that doesn't match the correct gears(ratios) selected and the rear wheel speed(speedometer)

So its very odd to not have a flashing OD OFF light(means transmission codes set) with what you describe

If throttle response above 45mph (OD on or off) is not INSTANT , i.e. no slipping(speed goes up with RPM), then torque converter has a problem

 

Sorry about the transmission numbers. I knew it was the one with the 4's in it (not the 5's) but couldn't remember the order.

Yes the speedometer works and with OD off the converter locked around 40 mph. Throttle response is not instant but doesn't feel like it is slipping and feels as a regular automatic transmission should be.

Once and a while I can get the OD off blinking but it goes off with a computer restart (turn the ignation off and on) and doesn't store a code. When it is flashing the transmission is definatly in limp home mode with late and hard shifts.

If I understand what you were saying when OD is on the convertor will not lock because the transmission wont go into overdrive and when I turn off OD it allows the convertor to lock?

Thank you for your help.

 

The torque converter locks on its own above 35mph, has been this way since very first torque converter(late 1950's), no slipping, this is why automatics got poor MPG, because most driving is below 35MPH
So the very very first thing that was added to eletronic automatics was a TCC solenoid, Torque Converter Control solenoid, it could lock the torque converter SOONER so direct drive, like a manual transmission, so better MPG

The torque converter is always locked above 35MPH it doesn't unLock to change gears, including OD
Gears are changed by clutches and bands(brakes), and it should be smooth but direct, no slipping
Slipping is BAD

Point of the torque converter is so you can stop when in gear and engine doesn't stall, it also multiples torque to get you moving better than the older, pre-1960s, hydraulic coupling units used with the first automatics
So best thing is for the torque converter to lock as soon as possible once you are moving down the road, and unless you are stopping, to stay locked as long as possible

Like when you let off the gas and are going downhill, if torque converter unlocked your speed would increase, like coasting in Neutral, but it doesn't, because engine is still connected so it slows down, called engine braking

 

Thanks Ron for the explaination about torque converters. I understand them but just don't want to put a overhauled torque converter in it to find I need a transmission or there was something simpler to fix.

 

Have a transmission shop do a pressure test on transmission, that will narrow down possible problems, and they will test torque converter as well

Good read here if you want to get a 400psi pressure gauge and fitting to DIY the pressure tests: https://atracom.blob.core.windows.ne.../2003_5_50.pdf

You should get pressure test before doing Stall Speed Test for torque converter
But just google: Stall Speed Test
If you want to see if its clearly a torque converter issue
But be aware that torque converter may not be the ONLY issue, so certainly not definitive test

I understand you want a direct answer, but that's not possible even for the most experience automatic transmission tech, which I am not and I assume you are not

Basically tests show what it isn't, as much as they show what it "might" be

Engines are much easier to diagnose than automatic transmissions, automatics have layers of interdependent functions, it is only ever, and always, a "best guess"