Torque Converter Clutch code P0741

[tomj76]

During my last three long trips I started having issues with the torque converter clutch. At about 150 miles into the first two trips the O/D light blinks and code P0741 is set. Then for the remainder of the trip the TCC never locks up (you can see that the RPM fluctuates with throttle position, rather than remaining steady).

However, after the engine has a chance to cool down overnight, the TCC returns to normal operation.

My main question for this post is if anyone knows if the PCM software stops attempting to use the TCC once the P0741 code is set during a "trip" (until the coolant temperature drops below the threshold value). It seems like that might be the case.

During my last long trip I didn't get the code, but I stopped for about 20 minutes at ~135 miles into the trip, then drove for ~140 mi to and stopped again for another 15 minutes, then drove the final leg of ~180 miles without ever losing the TCC or getting the O/D flash.

There may also be a leak at the input shaft, as I could smell transmission fluid when I stopped after the code was set.

I have a few avenues to pursue, but since it is intermittent it is obviously more difficult... I can change the transmission fluid/filter and replace the TCC solenoid. But my scantool doesn't read the transmission slip or the TCC apply ratio, so the information that I have when the problem occurs is very limited.

Right now I'd just like to know if the TCC is disabled during the trip after the P0741 condition is detected.

[LTDzak]

This is exactly what led to the demise of my 99 Windstar. If you want to monitor degree of slip on it you can use a tablet or other device with the Torq application.

Assume you are getting the flashing transmission light after 5 to 10 miles driving. On mine I got the code read at a trans shop that reads them for free, they said the van was done for.

There are 22 different things that go wrong that will cause the converter not to lock up on an AX4S AX4N. Nineteen or twenty of those involve the oil pump and various solenoids in the valve body. I got a Sonnax oil pump shaft off of Ebay, bought new oil pump drive shaft seals from Ford, and bought an expensive rebuilt valve body with known good solenoids. Didn't get it, would still fail to lock up. Also changed the fluid pan etc.

The other 3 items are the converter itself, there is an o-ring on the stator bushing, and the stator bushing itself can be worn. After trying the valve body I found a post on the net from a Ford tech that said the P0741 on a Windstar almost always meant the torque converter clutch was gone.

I drove ours back and forth to work for about a year and a half on the back roads, on ~ 42 mph stretches with very careful throttle application I could keep it locked. Finally decided to donate it to charity, it didn't sell at auction that I could tell.

If you decide to tackle the converter make sure you get the right one, 99-00 use a multidisc clutch and the later ones use a single disc. They have different number of tabs on the ID of the converter.

My big mistake was not replacing the converter when I swapped out the hydrolocked (wonderful intake manifold gaskets there Ford) engine for a low mileage one.

[LTDzak]

On your question, think the trans tries five times to lock the converter, if it doesn't get it it will leave it unlocked. There IS a sensor that senses converter RPM, one or two have had luck replacing that sensor. Once the trans cools off the PCM will try again.

[12Ounce]

Originally Posted by LTDzak

..... (wonderful intake manifold gaskets there Ford)......

I feel your pain! I have just made yet another effort to replace all intake manifold gaskets and seals ... trying to prevent cross talk between coolant and crankcase oil. If this effort doesn't work ... I'm giving up!

[tomj76]

Thanks for the reply.

It is possible that the TCC clutch is worn out. The aftermarket converter currently installed has at least 120,000 mi on it, so it might be worn out. However, I've had this code only three times, only after ~150 miles of continuous interstate driving.

I've also read that it can be caused by worn ATF, and while mine is up for the regularly scheduled change (36,000 mi), it is not severely worn fluid so it is a little surprising that it would be bad enough to allow TCC slip.

It has a fairly new TSS as well. I haven't driven it on a long trip since my prior posting, and the error code has not occurred since then during normal driving.

From what I've read, I agree that the PCM will try to lock a few times (your figure of five seems about right) and if it monitors too much difference between the TSS & engine RPM (corrected for gear/chain ratio) it stops using the TCC.

Once I replace the ATF & take a long trip, then I'll see if the code continues to occur.

[tomj76]

FYI, on the coolant/oil crossover...

I found that a failure of the front cover gasket can also compromise the oil. Also, when I rebuilt my engine I noticed corrosion pits on the head surface facing the intake manifold as well as the manifold surface facing the head. I couldn't get it machined without concern for changing the space between the two components, so I filled the pits with JB Weld and polished them with 1500 grit paper. I haven't seen oil in my coolant since then.

[12Ounce]

I've noticed the same pitting, and I have been very careful to maintain the coolant chemistry.

[tomj76]

When I was doing the rebuild I did some online research regarding intake manifold gasket failures, and at least one site suggests that the problem arises from abrasion of the rubber seals on the gasket, caused by the rough surfaces mating faces. They recommended a fine polish instead, which is the main reason that I polished them using 1500 grit paper. They were almost mirror smooth when I finished.

Here's a couple of links that discuss the problem:
http://www.agcoauto.com/content/news/p2_articleid/90
http://www.knowyourparts.com/technic...ket-diagnosis/

FYI, new MLS head gaskets require a finer finish than the older composite head gaskets. In this case it is because the coatings are thinner and cannot conform to rough surfaces. It is a little different than the intake gasket problem, but finer surface finishes seem to be a trend.

[tripletdaddy]

With all of the trans experts already here, I'd like to share my similar problem with my 2000 Winny, 3.8l, 140k. I suspect I'm having problems with the TCC as the van is stalling when coming to a stop, hunting, harsh shifts, and just recently got the codes P1741 and P0741. I'm trying to decide between several possible options and anything you folks can add. Irregardless, I will do a fluid flush and new filter and fluid. First, I could just replace the one or all five solenoids, which is the least I would do. Second, I could replace the five solenoids and rebuild the valve body. Third, I could get for a very reasonable amount of money on ebay a fully rebuilt valve body with all new solenoids for about the cost of a set of the five solenoids and a valve body rebuild kit. The only problem with this method is having to remove the valve body in a tight space with a lot of bolts, though the valve body may also have to come off if I rebuilt it. I understand that if there is debris, especially metal in the bottom pan, the valve body should be rebuilt. Yes? Anything else?

Lastly, any tips on gaining access to the cover and making the repairs? I've seen and read about getting at the cover without removing the trans.
Thanks

[12Ounce]

I know I'm a bit of a broken record on the subject ... which I know almost nothing about. When my tranny first exhibited this clutch issue, I ponied up about $1700 for repair. This was about at 100k miles. Up to that point in time, I had done a fair job of changing fluid (Mobil1) and filter ... but was plagued by a harness issue that caused violent and unpredictable shifting. Repaired harness. Tranny lasted until approx 215k miles and then broke a pump shaft ... probably weakened because of earlier harness issue.

At this point I opted for a Ford supplied reman. I was no longer willing to repair the tranny at local shops because I did not have any idea that all the compromised components would/could be discovered. Good price for reman. Came with all new fluid and solenoids (I looked). Supposed to include all new Ford upgrades. I added air/fluid cooler at about 300k miles. Wish I had done that sooner. Now at 450k miles; the reman tranny continues to perform flawlessly. The fluid stays clear and red (I probably haven't changed in over 150k miles.) I almost don't even check the tranny anymore. Getting careless.

Yes, you can remove cover with tranny in place.

[tomj76]

P0741 is a code that tells you that the TCC is not engaging (stuck off). Therefor you should see evidence that the clutch isn't engaged, such as engine RPMs that vary with the throttle position when you're cruising at highway speed instead of a steady RPM with vehicle speed, or no drop in RPM when the TCC would normally engage while cruising at a speed >50 mph.

P1741 is a code that says there is a control issue with the TCC. I don't know how it is unique from P0741.

The side cover can be removed without removing the transmission. I think you might need to pull the CV joint out to do this & remove the transmission mount. I had issues with thread damage when putting the side cover back on. It was related to damaged threads on some of the cover bolts. I had to insert a handful of helicoils to repair these holes.

Of course, be very careful of dirt getting in. I didn't try to remove the valve body in that position, so I don't know if it is feasible, but I think there is sufficient clearance to do it.

Stalling and strange shifting patterns can also be a PCM issue. For example, I had this problem when the VSS connector fell out the VSS on the passenger side of the vehicle. Difficult to repair b/c you have to take the y-pipe off to get to the connector. I've read that a faulty TRS is another possible cause of shifting issues. Stalling seems to imply that the TCC is engaging, and getting turned on when it shouldn't be. My first guess is the VSS data.

Also, I used some telephone wire, an electronics experimenters board, a few resistors and LEDs plus alligator clips and straight pins to make an indicator of the transmission solenoid voltages, to make sure the PCM wasn't at fault when my transmission wouldn't shift out of 2nd gear (limp mode). You should be able to check the VSS if you have a scan tool with live data or an electronic speedometer on your instrument panel.

Also:
http://www.justanswer.com/ford/4chhz...0-showing.html

[tripletdaddy]

Thanks guys. Lots to chew on. On another forum, an "expert" thought rather than a bad tcc solenoid the tcc is bad instead. He didn't explain why. He was so abbreviated and ran his points together, it was very hard to tell what he meant. He did provide some test procedures for those codes I have. Without getting into more nitty, gritty detail, from all of the symptoms and what I've read, etc., I would disagree on his diagnosis but that's based maybe more on gut and a more comprehensive view of everything. I've not read anything that really indicated it would be a bad tcc instead of the solenoid. Come to think of it, at least one code I've had clearly made it sound like it was an electrical circuit typed of problem. Perhaps the solenoid is breaking down, maybe overheated causing the body to swell and the inner rod is getting stuck. Something that I've seen in another application. I'd have to research a bad tcc before I consider it over the solenoid because that's all I've found to be consistent with all of the symptoms I'm experiencing. I also really don't want to drop the trans or pay for it to be done, especially when the idea is coming from someone that can't put together enough of two sentences to make clear sense. I wouldn't want him working on my car if that's the way he would explain to me what needs to be done at his shop. Seriously?
Thanks again guys.

[tomj76]

FYI, the TCC solenoid is not a typical "on/off" solenoid, but a pulse width modulated (PWM) one. The idea is that the PCM can gradually and adaptively apply the clutch (like a manual transmission) rather than slamming it on or being limited by a fixed apply profile that can be provided by an accumulator. It works by sending a pulsed voltage to the solenoid, and varying the % of time on vs. off to vary how far the solenoid valve is open. Advanced scan tools (not mine) can show the PIMs for the duty factor and the speed of the turbine (TSS) compared to the engine (RPM) [they call that slip or something like that]. It solenoid voltage can also be monitored with an oscilloscope.

If you don't have an advanced scan tool or oscilloscope, then you can cheat by making a little circuit that converts the pulsed solenoid voltage to a dc voltage using a resistor & capacitor. Knowing the signal to the TCC solenoid will let you know if the PCM is trying to apply the TCC in appropriately, or if the clutch is acting without a PCM command.

[tomj76]

After my first post, I saw the P0741 code on a trip <50 miles, plus a trip or two where it set after the first 100 miles. Then I stopped getting the code for a few months and a handful of trips.

Last week I was climbing a rather steep grade (5-10%) (2nd gear @ 30-40 mph) for about 3 1/2 miles when it started pouring out fluid from the front seal. Apparently the seal pushed out of the housing. I couldn't take care of this on my own, so I had it repaired at a shop. FYI, shop said this transmission design often pushes out the front seal from the housing, so they use Loctite when they install them. They also replaced the torque converter. I won't know if the new converter has fixed the problem unless it doesn't.

I've driven it on one long trip since the repair with no issue.

[tomj76]

Another update: The transmission had been trouble free during four to six 500 mi trips after the torque converter (and clutch) were replaced. However, during the last two (which were during fairly cold weather), the TCC error occurred again on the first one, but not the second one. I didn't check the code, but the O/D light was flashing and the tachometer showed higher than normal RPM and variation with throttle position instead of usual solid lock. It hasn't done it since (over about 800 mi of total driving, including one 500 mi trip)

Since the shop replaced the transmission fluid with the new torque converter, I think this suggests that the problem was not the clutch itself.