This 94 Explorer is sweet in every way but one. As I'm cruising down the highway, in OD, 60-65MPH, 1500/1700RPM, everything is wonderful. Cruise control is on, all is right with the world. Then.........Hey.......what is THAT! The RPM's jump to 2400/2500, and the volume goes up in the tranny. Not as loud as a kick-down to third, but kind of half way there. First time it happened that's what I thought happened...that it shifted out of OD and into third, but no.......I can manually drop it down to third and that jumps the RPM's up to 3000 or more with the expected increase in sound. This is like it finds something between third and OD. Can't get any pros around here to acknowlege this behavior as something they recognize, just what feels like a standard answer about a range of prices that you know will be the higher, regardless of the problem......anyone out there recognize this as a typical issue or had this happen to them? Please...not frantic about it, but it makes the mileage drop considerably, and I'm worried about it leading to something worse. THanks

 

sounds to me like your toque conv is unlocking which can be caused by a solonoid, valve or the converter itself

 

thanks for the quick reply.....any way I can tell which is causing this problem and what are the typical costs with replacing the converter

 

Replacing the torque converter will likely cost a few hundred dollars. There's the cost of the converter, and then labor, because the transmission (or the engine) has to come out in order to access the torque converter.
Of the three possible causes listed by TruFordguy, I'd say the torque converter is least likely to be the problem. Start with the electronic controls.
1st) Perform EEC-IV self diagnostic "quick test" (aka pull codes instructions at www.dalidesign.com/hbook/eectest.html). See what the PCM has to tell you. Correct any trouble codes that come up.
2nd) Inspect wiring in TCC solenoid circuit. You'll need a wiring diagram. Make sure all connections are good, no broken wires, and that you have 12 V to the transmission solenoids (powers both the 3-4 and TCC lockup solenod).
3) Perform output state test (part of EEC-IV dagnostic tests) while monitoring voltage drop across TCC solenoid. This will verify that the PCM "can" tell the solenoid to shift (seems likely that it can, because it does. It just switches off for some reason).
4 (and what could be most informative on an intermittant fault like this). Road test while monitoring TCC lockup circuit. See if the lockup disengaging is caused by an electrical fault, or the PCM's "choosing" to disengage solenoid. Recognize that, among things that could cause the PCM to "choose" to disengage the lockup, a bad ECT, TPS, or VSS could cause this problem. Complicating the diagnosis is the fact that the problem is "intermittant", sometimes it's there, sometimes it isn't. Any other observations you can make may help narrow down the cause (occurs at same vehicle speed, with or without cruise control, engine temperature, etc)