My 1992 Ford Explorer started shifting between "lock-out" and overdrive recently. It happens between 45mph and 55mph. It just shifts back and forth between "lock-out" and overdrive. According to the Tranny shop, switching to "Lock-out" is a normal thing but mine just goes back and forth between the two and it is really annoying. The shop said they "might" be able to fix it by replacing the "lock-out" valve.....
Anyone with similar problems?? Anyone to shed light on this? I had never heard of a "lock-out" gear before.....
I'm not sure what "lock out" gear is either but I must assume that we are talking about either overdrive "lock out" (accomplished with shift position selection) or torque convertor clutch lock up. Unfortunately, these are two very different things.
Looking at the speed range that your concern surfaces, I'll go out on a limb and guess that it's hunting between OD and direct (3rd)... If you have around 80K to 100K miles on the car, I can only think that it is nearly time for something expensive. This hunting is not 'normal'. At this point (no service manuals at home) I can only suggest checking fluid level and condition, the integrity of the hoses on the modulator line and be sure there are no engine performance issues (poor engine performance can and will manifest itself as a transmission concern).
I will suggest reserving the OD enable shift selection for highway driving and use the drive position for urban and hilly terrain driving. I have driven my '92 this way since I purchased it - now, with just shy of 109K miles and no problems...... YMMV
My '92 "shifts" in and out of lockup at about this speed range, based on gear lever position, throttle position, brakelight switch activity. TPS reads the speed that you move the pedal it seems, so a brisk application will unlock while a slow gentle push to the same end throttle position may not. Jim may want to jump in here and add to this. Pressing on the brake pedal far enough to engage the brake lights will unlock the TC clutch too.
Many moons ago I wrote up a situation where a bad plug wire was causing an intermittent miss, noticeable under load at around 55mph (speed limit at the time...). Another poster responded that he too had a similar problem, and that the miss was severe enough in his case to cause the trans to drop out of TC lockup. My instant advice therefore would be to look at all the things that might cause a miss that would affect the trans. Based on my own car's history, about 50K is the usable life of plug wires. If you have a lot more miles on your plugs and wires than that, it might do you well to get them replaced (or do it yourself) and see if the problem goes away. Wires are ~~$25 for good aftermarket. Plugs are cheap for copper, maybe a bit more for platinums. There's a sloew of opinion on whether you want to use platinum plugs, but that's a subject that deserves its own thread.
Hope this gets you headed in the right direction!
dr bob '92 XLT auto, with 170-some thousand miles on it. Still original auto gearbox.
Doing a little backwards research, I came upon a relevant popst fro sometime way back in the newsgroup history:
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has a note abouta defective throttle position sensor causing the problem you areexperiencing. Download a problem code for this and you may have foundthe culprit!
I posted this problem a couple weeks ago. The thing that fixed the problem is beyond me!. I noticed a small radiator leak a few days after I posted the questions. The Explorer never overheated but the tem gague did get on the high side a few times. I just kept filling with coolant until I could get a better fix. Finally this last week, I had time to flush the radiator and put in some "stop leak" fo rthe small pinhole leak.
Guess what? The "hunting" between the TC lockout and OD or DR is now gone!
There must have been either a sensor hetting too hot somewhere or maybe getting damp... I don't know but the problem is gone!!
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