Flaky TCC lockup when warm, 2000 5R55

abloy · March 10, 2008

Problem:

Truck has perfectly acceptable TCC behavior when cold, and typically for many miles after starting. Then, eventually, it will fail to lock up after starting from a stop, start the O/D light flashing, etc.

If one turns off the engine and restarts, the TCC will lockup, at least once normally, and it will stay locked until it would normally be released. Also, with the truck warm, careful accelerator application in either holding a steady speed of about 50mph or accelerating from a steady speed of 45 or so to 55 will cause lockup.

So, I've worked on a number of transmissions myself, but nothing in the Ford 4/5R family. I will get the transmission codes pulled, but to be honest, since it is entirely tied to the TCC activitiy, I'm guessing its a TCC code for excessive slip or whatever. I've been reading the heck out of the archives around here, and am inclined to suspect the solenoids (EPC/TCC) but do not know if the only when hot/always "reset" by turning the engine off nature of my problem matches up? Help?

Glacier991 · March 10, 2008

Hmmm let us know the codes. It could be a number of things, including the TCC solenoid, a tired EPC, or a spool issue, or even a wiring loom issue. (There are other possibles but way down the list in my mind's eye.)

abloy · March 12, 2008

Codes for TCC Issue

As promised, the codes:

PO741

and

PO1000 Drive Cycle Not Complete

There were also a bunch of random codes for other modules on the car, like "4-Low" indicator circuit malfunction, seat belt warning lamp malfunction, etc. The weird part is that NONE of those items are acting up whatsoever.

The local transmission shop, which has friendly and reasonably bright employees scanned it for free while I watched, and we discussed possibilities.

Glacier991: since you're one of the hard core transmission guys around here, do you have any ideas now.

BrooklynBay · March 12, 2008

Welcome to this forum! The EPC, and TCC solenoids are modulated, so they are considered high wear parts. How many miles do you have? Check this link for more information: http://www.explorerforum.com/forums/showpost.php?p=1724378&postcount=2

abloy · March 12, 2008

The truck has over 200k miles, however, i believe that it has had a transmission rebuild once already. I guess the question is more whether knowing both the symptoms and a the code, it can be narrowed down at all, or whether I should drop the pan, change the filter, throw a TCC into it, then if that doesn’t cure it, find a VB from eBay, or see if my transmission shop can sleeve the bore. Is the TC bore easily checked with the pan off?

The transmission shop that ran the codes is leaning towards TCC, just based on the way that it only occurs hot, and that lockup is solid when locked up. Though they’re not claiming to be experts on 5R55E issues.
o not believe that it is on its

Glacier991 · March 12, 2008

P0741 is a common code meaning that the TCC is not showing as locked up... or put another way there is slippage.

Let's talk about TCC operation. Inside the TCC there is another clutch like most any other in the transmission. On command it will "lock up" effectively giving you direct 1:1 lockup with the engine crankshaft. In the 5R55E (and in most modern autos these days) the engineers have figured out ways the "feather" (read slip) that lockup to make for nicer shifts and lockups. They do this by "modulating" the pressure application and measuring the slippage (which is why the computer can read TCC slippage - it is part of a feedback loop for that modulated shift/lockup). Ok, what your computer is saying to you is in effect : "HEY ! I locked that sonofagun up, but when I check, that bugger ain't locked, there is some slippage!". All right then, let's ask why do clutches slip?

Clutches slip for a number of reasons. If the apply pressure is not adequate - they slip. If the clutch surfaces are burned/glazed - they slip. If the fluid properties are not up to snuff - they CAN slip. (Note the added CAN). If the clutch surfaces are otherwise damaged - they slip.

Believe it or not, there are two properties of ATF that come into play. The ability to help a friction bring a rotating object to a stop, and the power to help that same element hold it stationary. So, in order of ease of solving this problem, when was your last fluid change? Make sure you are using Mercon V or equivalent. If it has been a while (60,000 mi or so) let's start with a fluid change. Believe it or not, THAT could do the trick.

But what if it doesn't you ask?

Ok let's look at the list. The last one - damaged frictions seems to be ruled out by your working TCC clutch cold. While it won't rule out glazing per se, it goes a long ways towards that end, so for now I will rule it out. What's left? Inadequate apply pressure.

TCC pressure in the 5R55e is controlled by the EPC, the pressure regulator, the TCC solenoid and the TCC valve. The TCC bore is a known high mileage leaker... even if everything else is doing its job if the pressure is leaking away faster than it can be built up you will have slip.

In order of ease once we get to this point is the replacement of the EPC and TCC - the two modulated and thus "high wear" solenoids. Sometimes renewing them can solve the problem - not always.... but that is a pricey proposition - replacing both will set you back nearly $200. What if that does not do it, you ask? Then you can either sleeve the TCC bore (itself a pricey proposition) or replace the VB.

At the end of the day, if the fluid change doesn't get it, I'd be tempted to tell you to get a remanufactured VB from Central or some other reputable seller and eat the $300 and be done with it. If the fluid changes doesn't fix it, I am betting that will.

Hope this helps.

abloy · March 12, 2008

Thanks.

Wow, thanks. This is a nice, and helpful board!

Glacier991:

I tend to agree that since lockup cold is fine, and when one shuts the truck off hot, you get solid lockup, I don't think it is likely that the Torque Converter is toasted and incapable of good lockup.

I bought the truck used, but it had very good maintenance before I had it. So I can't be certain that the small town ford dealership did a recent fluid change, but it is likely. They may, however, have screwed up somehow.

Some new questions:

1. I used to (On ford C5 and GM 700R4) flush the fluid by pulling a line off the cooler and adding fluid to the dipstick in small increments. I'm tempted to allow the relatively reputable local transmission shop to do a low pressure flush with their machine, and duplicate this complete fluid change. Is this a bad idea on a 5R55E?

2. No matter what else I do, I want to do a pan drop/partial fluid change with good fluid soon. Is there any particular brand of fluid or filter that is better than another?

3. Would it be bad to just install an eBay VB like this one:

http://cgi.ebay.com/ebaymotors/FORD...010QQitemZ200207459636QQrdZ1QQsspagenameZWDVW

and a new TCC, and call it good?

Glacier991 · March 12, 2008

ATF... non-synth... is ATF. Brands matter not. Your idea of the change by disconnecting a line and adding as you pump out is my main method.... and frankly no different than a paid "flush" (just $60-100 cheaper). Either works for me. If you feel a need to addd something to the fluid, all I recommend is Lugegard platinum in your situation. NOTHING else has my recommendation.

Some folks may have noticed that in my last few replies I have suggested buying a remanufactured VB. This is not because I have shied away from the DIY rebuilds when appropriate, but because in these instances the issues do not suggest a simple VB rebuild in a high mileage 5R55 will be successful. My best guess in your case is that your TCC bore is ovalled and leaks like crazy... a brief shutdown allows temps to normalize enough to close up the leaks briefly.

Hence my advice that when and if the fluid change does not work (assuming it does not - but is a good idea and NOT wasted money anyway) you buy a rebuilt VB for your model. I am not a big fan of used "tested" E-Bay 5R55E VB's as drop in replacements. I can explain that in another post.

I have had people for whom the fluid change in your situation has worked...

Oh, and, there is only ONE filter I recommend. FRAM microfelt. FORD OEM and aftermarket.

(yeah I guess I AM an opinionated SOB too)

BrooklynBay · March 12, 2008

Sonnax makes a valve body test plate for testing individual sections of the valve body if you want to troubleshoot: http://www.transmissionpartsusa.com/WET_DRY_Air_Test_plate_p/400-000swatp1.htm

Sonnax has a free valve body training video on a DVD which explains how to use one of these test plates: http://www.transmissionpartsusa.com/DVD_07_Sonnax_valve_body_traning_video_p/400-00vbdvd07.htm

2004sporttrac4x4 · April 12, 2021

Ok so I have been chasing this issue on a friend of mines 2004 sport trac. It has the OD light flashing and I was able to get a local shop to scan if for me. It is the P0741 code. So far I've changed trans fluid and the TCC solenoid with no luck. I have test drove this truck and the light will flash as soon as it gets up to speed. Doesn't matter if it's cold or hot. I have not felt the TC clutch engage at all.

I've been following the advice on this thread, and my question is: is there a way to find out if the problem is in the VB or in the TC itself? Don't want to throw parts at it, especially a new VB or TC and it not solve the problem. Thanks

imp · April 13, 2021

Glacier991 said:
P0741 is a common code meaning that the TCC is not showing as locked up... or put another way there is slippage.

Let's talk about TCC operation. Inside the TCC there is another clutch like most any other in the transmission. On command it will "lock up" effectively giving you direct 1:1 lockup with the engine crankshaft. In the 5R55E (and in most modern autos these days) the engineers have figured out ways the "feather" (read slip) that lockup to make for nicer shifts and lockups. They do this by "modulating" the pressure application and measuring the slippage (which is why the computer can read TCC slippage - it is part of a feedback loop for that modulated shift/lockup). Ok, what your computer is saying to you is in effect : "HEY ! I locked that sonofagun up, but when I check, that bugger ain't locked, there is some slippage!". All right then, let's ask why do clutches slip?

Clutches slip for a number of reasons. If the apply pressure is not adequate - they slip. If the clutch surfaces are burned/glazed - they slip. If the fluid properties are not up to snuff - they CAN slip. (Note the added CAN). If the clutch surfaces are otherwise damaged - they slip.

Believe it or not, there are two properties of ATF that come into play. The ability to help a friction bring a rotating object to a stop, and the power to help that same element hold it stationary. So, in order of ease of solving this problem, when was your last fluid change? Make sure you are using Mercon V or equivalent. If it has been a while (60,000 mi or so) let's start with a fluid change. Believe it or not, THAT could do the trick.

But what if it doesn't you ask?

Ok let's look at the list. The last one - damaged frictions seems to be ruled out by your working TCC clutch cold. While it won't rule out glazing per se, it goes a long ways towards that end, so for now I will rule it out. What's left? Inadequate apply pressure.

TCC pressure in the 5R55e is controlled by the EPC, the pressure regulator, the TCC solenoid and the TCC valve. The TCC bore is a known high mileage leaker... even if everything else is doing its job if the pressure is leaking away faster than it can be built up you will have slip.

In order of ease once we get to this point is the replacement of the EPC and TCC - the two modulated and thus "high wear" solenoids. Sometimes renewing them can solve the problem - not always.... but that is a pricey proposition - replacing both will set you back nearly $200. What if that does not do it, you ask? Then you can either sleeve the TCC bore (itself a pricey proposition) or replace the VB.

At the end of the day, if the fluid change doesn't get it, I'd be tempted to tell you to get a remanufactured VB from Central or some other reputable seller and eat the $300 and be done with it. If the fluid changes doesn't fix it, I am betting that will.

Hope this helps.

One point missed: The TCC lockup CANNOT occur with a cold transmission. The fluid temperature sensor tells PCM disallow TCC engagement until warm-up is acceptable.

So, how are we assuming the TCC is locking up "cold"?

transman304 · April 13, 2021

You will need to get a live data stream and be able to monitor what’s happening. The TCC system in this unit has several problem areas. When the light starts flashing does the transmission go into failsafe mode?
Brad

2004sporttrac4x4 · April 13, 2021

imp said:
One point missed: The TCC lockup CANNOT occur with a cold transmission. The fluid temperature sensor tells PCM disallow TCC engagement until warm-up is acceptable.

So, how care we assuming the TCC is locking up "cold"?

Imp, well if that is the case, then it must warm up very quickly because as soon as I take the truck to 45 - 50 mph, the OD light will begin to flash. Meaning the code is set and the TC was given the command to lockup. Doesn't matter if the truck was sitting over night.

2004sporttrac4x4 · April 13, 2021

transman304 said:
You will need to get a live data stream and be able to monitor what’s happening. The TCC system in this unit has several problem areas. When the light starts flashing does the transmission go into failsafe mode?
Brad

Brad, yes, it does seem to go into a failsafe mode. The only reason I think it is is because the truck will begin to shift hard once the code is set.

transman304 · April 14, 2021

Sounds like what you are experiencing is the PCM commanding high line pressure to try and compensate for the slip it detected. Fail safe is when the transmission defaults to 3rd gear only.
Brad

2004sporttrac4x4 · April 14, 2021

transman304 said:
Sounds like what you are experiencing is the PCM commanding high line pressure to try and compensate for the slip it detected. Fail safe is when the transmission defaults to 3rd gear only.
Brad

That makes sense. It does feel like the pressure has been increased. So the PCM will do this when it detects slippage? It only does it once code is set. Apparently the increased pressure isn't enough to reduce slippage or engage the TCC. What would cause it to go into failsafe? The truck is definitely hitting 4th.

transman304 · April 15, 2021

Pressure rise is trying to preserve transmission after component slip is detected. It will eventually go into a failsafe as the transmission problems persist and will set a hard code. Problem will definitely only get worse.
Brad

Flaky TCC lockup when warm, 2000 5R55

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