Torque Converter Clutch code P0741

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.

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.

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.

..... (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!

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.

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.

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

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/technical-resources/engine/intake-manifold-gasket-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.

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

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.

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-ford-windstar-1988-windstar-code-p1740-showing.html

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.

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.

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.

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.

I've taken two more trip over the last month and had no issues with the TCC code.

New update:

The new Torque Converter did not permanently resolve the P0741 code. I've been getting it randomly on various trips over the past year or so. It seems to be related to driving conditions that require a lot of TCC apply/release cycles, but it isn't a sure thing. I seem to get the error code more often when driving through mountains or highly congested traffic, but I can drive through those conditions without getting the code.

When the code occurs it always causes the PCM stop attempting TCC lockup until the vehicle is stopped and cools down.

This happened on my most recent long trip, the code was set while driving to the destination and and again when returning. It started within 200 miles of the start of the trip and within less than 100 miles during the return.

However, on the return trip I did something I've never done before. Since I had my scan tool with me, I erased the codes after the P0741 appeared. Erasing the codes also resets the TCC "lockout flag" so that it can be used again. That's great, but the error would reoccur immediately (within seconds, not even the "five try rule" noted previously), but only if there was TCC activity. After some fooling around I was able to reset it and then set up the scan tool to report TCC apply ratio, engine RPM, and Transmission Turbine RPM before the error occurred again so that I could see what conditions might be causing the error.

What I found was that the TCC would re-engage without any errors and stay engaged for long periods of time over several miles of driving, but the error code was reported the moment the TCC was released. This is the complete opposite from what I expected.

Since the P0741 code is an error stating that the PCM is not detecting TCC lockup, which implies an attempt to engage the TCC has failed, I thought this would register when lockup failed, but instead the error code is reported when the TCC was released after a successful apply.

So, no error occurs if the PCM never attempts to engage the TCC, or if the TCC is engaged and the conditions for TCC release (zero throttle, down shift, brake apply) are never seen by the PCM.

The other point of interest is that after a dozen or two code resets and about 100 miles of driving, the TCC started working normally again, and P0741 never occurred during the rest of the trip (another 300 miles).

I don't know what is going on, but this certainly fills in the picture a lot more. The fact that it starts randomly, but also can start working again suggests that there is an intermittent problem, but whether that is electrical or hydraulic remains to be seen. I doubt that this is an issue with bad o-rings or anything to do with the clutch itself.

What I don't know about transmissions would fill the cloud, but I have experienced this code twice on the Winney. Once at about 215K, once at about 480K. In both instances the clutch friction packs were "replaced". The first incidence by replacing whole tranny, the second by doing a rebuild in local shop.

As I understand: The torque converter is filled with fluid from the internal pump, and the pump is driven through the various clutch packs from the converter,... as the packs wear (and lose thickness), there is less pumping pressure to fill the torque converter.

Things go down hill quickly from there ....

Even with clean Mobil 1 fluid, I don't expect much over 200K miles before another rebuild and friction pack replacement.

Took it on another long trip, and it did the same thing again, on both legs of the trip.

It happened each time after 30 minutes of driving, after getting to road conditions where I was cruising at ~70 mph.

It hasn't done this on any short trips (i.e. less than 30 miles).

When it did it during the "to" trip, I tried to reset the PCM to get the TCC working again, like I did on the return trip back in Nov, but the code would reappear as soon as the codes were reset. I tried for about 40 minutes and decided to let it be after that. I noticed that the EPC (electronic pressure control) was "locked in" at 60 psi once the code was set, and would only occasionally move to a different pressure, even when stopping. I've read that the EPC is supposed to modulate with load conditions, and I've see this too while driving the van with the scan tool connected.

On the drive back, the code occurred again, but this time I was able to reset the PCM and restore operation of the TCC. I noticed a few things this time:

- Before the code occurred, I noticed that engine RPM stayed high rather than dropping in driving conditions where the TCC would normally lock up. In fact, I was watching the TCC% PID go to 100% without any corresponding drop in engine RPM when the code occurred. This confirms that there really is a malfunction and the PCM is correctly setting the code since it is specifically looking for a difference between the engine RPM and transmission turbine RPM when the clutch is commanded to close.

- After the code was set, but before the reset, the EPC was stuck at ~60 psi and the transmission fluid temperature increased to 180 - 210 degF, which is probably due to the energy from fluid friction in the torque converter without the clutch operating.

- After resetting the PCM, the EPC pressure reading started modulating again and TCC engagement seemed to require about 54 psi to occur. Once the TCC started working again the fluid temperature fell to 150 degF and stayed there except when climbing long grades where the clutch has to be released by the PCM. I had previously thought that overheating fluid might have been the cause because when I'd read the fluid temperature PID after the code it was always going up.

Just like in Nov, the van never set the TCC code again during the rest of the trip (a total of 500 miles).

I believe it could be either a hydraulic control issue or an electrical issue, meaning either the TCC solenoid or EPC solenoid are malfunctioning, the valve body is sticking, or there is an issue with electrical connections either in the transmission or PCM.

I don't believe that it is a problem with worn friction surfaces since the TCC is new and it is only 70,000 miles since it was rebuilt, plus the measurements that I took of the friction plates showed very little wear when compared to the new ones.

I just don't understand with any of the potential causes why I can reset the PCM and get normal operation for such extended periods without any reoccurrence.

Some more experience on this code....

Now the code will set after only ~12-20 miles of highway driving. I can see that the engine RPM doesn't come down to match the TSS rpm when the TCC tries to engage, then code sets. I don't know how an extended period of driving on local streets affects this. At first, clearing the code will show the same results, but after driving for another 30-60 minutes and clearing the code, the clutch will start engaging again. At this point the code might not occur any more during the trip, or it will show up when releasing the clutch (weird!).

Now that it happens more predictably in a relatively short period of time, I think I need to monitor the TCC solenoid signal from the PCM as well as checking the regulated pressure at the transmission. Hopefully this will provide some insight as to where the fault lies.

I haven't been driving the Windstar as often, and I have not taken any pressure measurements, but I wanted to add some recent experience on this issue. The fault stopped occurring regularly in the first miles of a trip. The only thing that I thought had changed was going to winter temperatures. The last long trip I took in March did not have any occurrence of the P0741 code. Also, the more I see of this, the more I think the issue lays with either the PCM itself or the data that the PCM receives.

Note that these descriptions are for highway operation, usually interstates, usually on relatively flat terrain or sometimes in mountain areas.

-It is not related to transmission temperature... it will occur at just about any transmission temperature.

-If the vehicle is driven far enough after the code occurs, a code reset with resume normal operation of the TCC for the entire trip.

-It seems more likely to occur when driving in conditions that cause frequent TCC release/lockup cycles.

-I have seen the PCM set the P0741 code when my scan tool reported 100% TCC application (which should have locked the clutch) but the engine RPM did not fall to reflect the action of the expected operation of the clutch.

-After the P0741 is set, the TCC is disabled and the PCM does not attempt to lock again. The transmission oil temperature increases from ~170 degF to 300 degF when operating without any use of the TCC.

-After normal operation is resumed through OBDII code reset, the transmission temperature slowly decreases to the normal (~170 degF) operating point. If the code were related to the transmission temperature I'd expect it to reoccur when the temperature dropped back to normal temperature.

-The P0741 code has never re-occured after normal operation has been achieved. However if the reset is used too soon, the P0741 code will usually reoccur, but in different ways: (1) immediately on the first attempt to apply the TCC (2) immediately, but after the TCC was applied, RPM dropped as expected, and the code is reported when the clutch is released after the successful lock. The second style of error surprises me, since the code is reporting failure to lock, not failure to release.

-I have seen where the P0741 code did not occur over a period of multiple trips because a misfire code was stored from earlier malfunction of a fuel injector. Also, the P0741 fault began again as soon as the fuel injector was replaced and the PCM was reset. It seemed that the misfire code was able to prevent the P0741. I did not notice any inconsistency between the operation of the applied TCC and the engine RPM during the period when the code was not occurring, so I don't believe the fault was happening but not getting recorded.