T/C Unlocks Occasionally

[AlanS]

I'm posting this question to see if anyone else has experienced this.

I have a 96 F250 with E4OD tranny. About 160K on truck. I have no idea if trans was ever rebuilt, bought truck used.

Occasionally, and I mean maybe once or twice a week, it feels like the torque converter will unlock when the truck's at speed. That is, running down the road at 60 to 70 MPH, all of a sudden the RPMs will increase from 300 to 500, or so. Sometimes this corrects itself. Sometimes I can kick it into 'passing gear' and when it comes out, the TC locks up. After this occurs, it won't reoccur usually for days. Each episode lasts no longer than a minute, or two at most.

I had the tranny 'flushed' (all fluid exchanged) about 6K miles ago. In a subsequent filter and fluid change, there was a LOT of metal 'dust' in the pan. Synthetic fluid was installed after 'flush', about 14 quarts or so, as I recall. I recently had filter and fluid changed again Not a complete flush, just the pan dropped and 7 or 8 quarts or organic fluid replaced. I'm going to go back to organic fluid versus synthetic.

I'm thinking the 'flush' was a bad idea and stirred up and suspended a lot of this metal 'stuff', and some of it's clogging valves/passages etc., from time to time.

Temperature doesn't seem to be a factor. It does it when it's cold, or when it's warm. Sometimes it occurs within 15 minutes of engine start, and sometimes it might be an hour or two after. I don't really see any type of pattern related to weather, temperature, or vehicle speed. Also, this occurs on flat land, so there's no increased load on transmission when it happens.

The trans shifts normally in all other regards. No after market shift devices or performance programs (though I had both in past) are installed.

It seems to me there is no hard mechanical problem with the trans, or things would be more consistent. So I'm thinking the fluid is either contaminated, or maybe the electronics are a little 'funny'.

One other thing: the OD light in the shifter has never worked, i.e. it's always off and clicking the button in the end of the shifter has never done anything--I think there are some wiring issues in the shifter or elsewhere. But this symptom I'm describing was not always present. It seemed to surface after the tranny 'flush'.

So anyone seen anything like this before, or have any ideas? Thanks for any of your insights, and help...

Alan

[IHwelk49]

Yeah the trans flush probably wasn't the best thing, There is a check valve in the pump that operated TC lockup that valve could be sticking. It also could be something in the Electronics- the shifter, solenoid pack, or even a speed sensor. I would get it scanned to see if theres any codes.

[AlanS]

I had the pan fluid changed and the filter replaced and the frequency of the unlocking has been reduced. It has actually only done it once in the past few hundred miles whereas before this last fluid change it was doing it every 100 miles (couple days) or so. Thanks for the comeback, IHwelk49. I would say the 'flush' was a bad idea, and some of the crap it stirred up wound up plugging things up. I won't do that again. Fluid change ok, but not the flush...

[ZachBoyer]

When I hit my brake while still on the gas the truck will knock out of overdrive into the half gear lower it seams. I also had this problem with my trailer wiring. It was doing it non stop and some wires in my trailer were shorting out...

[AlanS]

ZachBoyer, mine was unlocking just cruising down the road, no brakes or gas, just moving along in cruise-control. Doesn't sound like the same problem as yours, but I'll keep the wiring (electrical) in mind in case the problem continues to get worse. Thanks for offering your help.

Alan

[sikktruk01]

not sure if this will help but it's very informative.
Complete E4OD High Performance T

[Gruss]

Check your tail/brake lights for loose filaments or corrosion. When the brakes are applied that is a signal for the converter to unlock. Sometimes the bulbs will short out causing the converter to unlock.

[Dmitri]

Originally Posted by sikktruk01

not sure if this will help but it's very informative.
Complete E4OD High Performance T

jesus lord,whoever did that write up is a genious
god bless him

[AlanS]

That's interesting about the brake lights, I'll check that.....that article is well presented. Hope mine's not ready for a rebuild just now, though...

Alan

[AlanS]

A follow-up to my original post...

I've been doing some off-roading here in the desert. The other day I went up a road that had a 'washboard' surface for several miles. Real rough. I fiddle-futzed around a while, finally went back out and hit the paved road, headed for home.

My T/C wouldn't lock-up at all. I didn't put 2 and 2 together for a while. Figured whatever was going on had finally reached its conclusion, the T/C was shot, and might as well do a complete tranny rebuild while I was at it.

Then I started pricing out rebuilds and thought maybe I'd exhaust all possibilities before I did that. I'm poor and don't have 2 grand or better right now to pay someone, and too chicken (and dumb) to venture a rebuild myself. (I'm not too partial to the eBay trannys as they seem like a crapshoot what with having to ship it to me, then ship my core. If everything comes off good the first time, great. But any problems could wind up being a real hassle.)

So I start searching the internet for E4OD, and get some hits in other parts of this forum, and one or two other forums. I come up with search terms "FIPL", "Tach Sensor", "Speed Sensor", and "MLPS". Have no idea precisely what these are, but poke "E4OD FIPL" into the Search tool, and it comes back with a thread where another guy, with a pre-Powerstroke is having a similar problem of the T/C unlocking randomly.

It was a good thread in that several things were offered. The first thing was a guy says: "Did you check the plug on the side of the tranny? Make sure it's clean and all the pins have good contact."

Long story short is that appears to be where my problem is. I had installed a Banks TransCommand a couple of years ago. It spliced into the solenoid plug (passenger, rear of trans). There's a couple plugs in that region, one from the Banks, and the standard plug; some pins were pushed in on both plugs, not making contact. Everything was muddy/dirty. I cleaned everything up, and pushed the pins back into place. I need to replace the main plug which has seen better days, but the deal is, the trans is shifting normally now, including the T/C locking-up normally.

Too soon to say if this was the original problem, but I suspect it was this plug, all along.

During my repair work before I got everything sorted out, I test drove it several times, with various of the pins not making contact. I had every symptom in the book, no shift out of first, starting out in 3rd gear, 'bucking bronco syndrome' (don't know what that was, seemed to be rapidly shifting between a lower and higher gear, simulating an unbroken stallion.)

Moral to my story: If your transmission is acting weird, check the plug on the rear of the tranny, passenger side, behind the heat-shield, and make sure it's all kosher. Could save you a lot of time and anxiety.

Alan