2005 Pontiac Vibe P0741 TCC Solenoid troubleshooti

I don't know if it's the same other scantools but trying to do transmission bi-directional controls with a Snapon product is not a fun task. Especially KOEO and especially TCC solenoids. Mid 2000s and newer Fords are the worst for that. They give you a list of like 8 different criteria you have to meet to command any of the solenoids. Even running and meeting every criteria I've had a few not allow me to run the tests. Also Snapon likes to pulse output controls. Totally threw me for a loop the first time I was trying to test a fan bi-bidirectionally. I thought I had a relay problem until I realized it was just the scanner intentionally pulsing it on and off.

Shift solenoids are a lot more forgiving though. As long as you're at a low speed, or KOEO, then for the most part they don't care if you toggle a solenoid one at a time. It's not any different than requesting a different gear. As long as you're at a low speed then it won't harm anything. That's why they don't let you do the test at a higher speed. So you don't accidentally hit 1st at a high speed and start burning things up. TCC is the opposite though. Newer vehicles are very cautious about giving you control of that. You start applying the TCC at low speeds then best case scenario you burn up the clutch and need a new torque converter. Automatic tranny clutches are holding members. They are PAPER thin! Worst case scenario is the converter grenades sending metal through the tranny then you're looking at a whole new transmission.

I also never trust transmission bi-directional tests when a car is on a hoist. If you want to do the test properly in a shop then you need a 4 wheel dyno. You start flagging ABS codes and a lot of vehicles will deny you transmission bi-directional controls. When this happens Snapon scantools don't always warn you this is happening. Again, I'm not picking on Snapon, I'm just mentioning them because they're what I use. I'm not sure how other brands work in these scenarios.

Whenever I have a TCC issue the first thing I like to look for is TCC slip when it applies on a road test. I'm lazy. Ripping stuff apart involves work. I like to park my butt in the driver's seat with a computer on my lap for as long as I can. You just have to hope the scantool gives you data for TCC slip. Sometimes you'll get a data pid that says TCC Slip RPM or other times you'll get an Input RPM or Turbine RPM speed. In which case you'll have to subtract that from Engine RPM speed to get your TCC Slip. You'll also want to make sure the TCC is fully applied. If it's an on/off solenoid then the PID will usually say applied/not applied. If it's pulse width modulated then you'll usually have a TCC % PID or the TCC PID might say not applied/partial/fully applied. Chrysler calls it an Electronically Modulated Converter Clutch (EMCC) so they usually have a pid that says not applied/partial EMCC/full EMCC.But either way, with the TCC fully applied you should see less than 10 RPM difference between the converter impeller (Engine RPM) and converter turbine (transmission input speed). Ideally you want to see less than 5 RPM.

This test gives you a chance to test the mechanical/hydraulic side of the TCC. If the TCC is electrically fine but the solenoid is mechanically damaged/restricted or there is a loss of hydraulic pressure then you can get a TCC Performance Code. I like to do this drive cycle test first because it's easy and helps me stay on track when I'm doing under the hood tests.

Electrically you've tested the ECM harness down to that solenoid ground and everything checks good electrically. I'd say the next test is to backprobe the TCC Solenoid Control wire at the ECM in a graphing multimeter on the Verus at the same time as watching live data. Compare the voltage to TCC Apply, Engine RPM, Engine Load, any kind of TCC Slip or Trans Input Speed, etc.

The line pressure control solenoid code of the other computer is a bit worrisome. That's the most important solenoid in the whole transmission. Some call it an EPC, SLT, LP VFS, etc. It's like the Holy Grail of valve bodies. If you have an issue with that it can, and usually does, throw out anything and everything in the transmission.

Trannies can be ugly and you really have to pay attention to the wording. The code said, "TCC Performance or Stuck Off". If it says any of Circuit/Open/Low/High/Short then you're usually good to stick with electrical but any tranny code that says 'Performance' can have a wide array of causes...

And don't forget the Victory Beer when you're done! Most important part of any difficult diagnosis! :lol:

Haha I just realized I posted this in the wrong spot. Probably should be in: ScannerDanner Premium ?

I was just thinking about this video!
I think this area is fine for this thread, it is a case study video after all. Could go in either section I suppose.
I was thinking the bidirectional test of the TCC was valid, but I'm not so sure now. In my experience, if the criteria noted is critical for running the test, then the scan tool will just boot you out. I could be totally wrong in this instance though. It would be kind of stupid (dangerous) of them to not even let you open the test until you're up to cruising speed
Tough to say without trying it driving. I probably would have jacked one front wheel off the ground and tried it in drive, to hell with the abs.
I'm satisfied with the circuit integrity and the condition of the solenoid, but like you said, "performance" codes can be generated for a whole variety of reasons. I think code set criteria will be helpful in nailing this one.
I'm glad you commented on this one, you've got far more transmission experience than I do. It's cool to see what you're thinking coming from your background.
Waiting on part two for sure!

Also, I know what you mean about the Snap-On tools cycling the outputs on and off. That caught me off guard the first time I experienced it aswell.

Yeah, it'll definitely be interesting to see what this one ends up being when part 2 comes out.

Noah wrote: Tough to say without trying it driving. I probably would have jacked one front wheel off the ground and tried it in drive, to hell with the abs.

Heh, I'd be more worried about diff gears than ABS with doing that...


My feelings on something like this is if you activate the circuit bidirectionally KOEO and you get proper output on the control wire then that's good. You've verified all that works. But if you get nothing then I personally would only trust checking it on a road test. If you tried it KOEO and got an error message from the scantool then I might try it up in the air. But if not then I wouldn't trust running in the air anymore than I would KOEO on the ground. Ultimately I really don't trust transmission bidirectional controls to call a computer.

The one thing that would be nice is at 16:35 in the video. He activates the test and the TCC Enable PID stays off. It would be nice to clear the codes, try to activate it then check for codes. If it flagged a code right away then I'd feel a little more comfortable with it. If it didn't flag any codes then I have way too many doubts and am still wondering if that command was intentionally ignored. Doubts that could only be cleared with a road test.

This also isn't normally a very high stress driver. Especially with the solenoid appearing fine electrically and the ECM living in a pretty safe spot. Sure, you can always have a random circuit board failure but this is just an apply and hold driver. It supplies a relatively low current and really doesn't cycle very much. A fuel injector driver probably cyles 10,000+ times for every one of the TCC.

It very well could be just a bad computer. You just gotta be sure with trannies. Bills can go from hundreds to thousands in a scary short amount of time... :blink: So ya... part 2 should be a gooder

ONE front wheel Noah?! Savage! Haha. At least lift two!!

I was just coming here to make this thread! :lol: Well done ecwurban. Like Noah said, I'm glad you commented on this one.

I'm really glad to hear you guys are wondering about A.) the bi-directional test, and B.) the code definition. I'm pretty sure that, in this case, the car needs to see vehicle speed higher than 30 MPH to allow the TCC. I saw the "TCC Enable" PID, too, big flag right there.

The code itself still bothers me. The description says 'stuck off', but that could be down to a hydraulic issue inside the valve body, or the clutch itself. Like ecwurban said, I'd have wanted to see how the engine speed and input speed sensors behaved on the highway first. Also, did they say they checked fluid level? :huh:

Really not trying to be critical of Paul here One of the things I respect most about his channels are that he shows the twists, turns, and occasional mistakes that happen in the diagnostic process. If this turns out not to be an ECM problem, then hey, no hate from me

Definitely not knockin on Paul. It can be hard to catch things live. I'm always realizing stuff after the fact. Once I've had some time to reflect on it while being detached from any distractions. The fact that he does this stuff while not only teaching a class but also filming never ceases to amaze me. My hat is always off to him and all that he does. Plus this is the reason why I love doing this stuff. No matter how good you get and how much experience you have there are always new things to learn and improve on!

Decided to go digging in the comments on this video, found this gem:



Looking more and more like an internal trans problem

Part 2 is now available. I'll try to contribute to this thread after you guys watch it. Thank you!

Trannies can be really annoying. Be happy you didn't have to go any further!

Generally speaking, if a transmission control component has an electrical fault it'll almost always flag a DTC that says "circuit" in it. Most ECM/TCMs in the last 10-15 years are really good at monitoring transmission electrical components. I have a high degree of confidence in live data for transmission solenoids being electrically accurate. In that if a PID goes from Off to On I feel pretty confident that it got the proper control. If there's a problem on the control side then the PID will almost always stay Off. It's not a bad idea to check manually but I'd put that further down the list. At this point you're just sitting in the driver's seat looking at scantool data. Next easiest thing is to go for a quick road test while monitoring live data and getting a feel for the health of the transmission.

But ya, let's say this is a customer's vehicle and they want it fixed. Say you've ruled out everything electrical. Now's where things get really ugly...

You've got four basic possibilities. It can be a solenoid/solenoid pack issue, valve body issue, internal transmission issue or the converter itself. The problem is if you guess one and get it wrong then things can very expensive very quickly. Also if you try to properly diagnose the issue then that gets very timely and also very expensive very quickly!

I'm in Canada and a city of 150,000 people. I'll give you prices from my area because that's what I know. These are full retail parts and labor prices with sourcing parts from reputable parts stores. Sure you can get ultra cheap, offshore parts online but have fun with those... These also are for new/reman parts. Not for anything used/salvaged.

Let's say you want to go after the solenoid and it's a simple solenoid. You'll need to drop the pan. Depending on if you're going to change the fluid, filter and gasket and depending on if you're just going to change the solenoid or if you're going to manually energize it and air check it then you're looking at $150-$330. Keep in mind it takes time to pull it out and manually check it. In the retail world that costs money.

If it's a whole solenoid pack then most newer ones have gone to complete, non serviceable units. These are pricey, usually involve dropping the whole valve body and usually can't be manually checked. Good luck getting any kind of internal info on them... Labor wise you're usually looking at 1.5 hours to 2.5 hours to replace the solenoid pack and put everything back together. Parts cost is usually $300-$900.

If you're going to replace the whole valve body then you're usually looking at 2 hours labor and $800-$1800 for parts. Some have internal TCMs that require programming. If you're going to try and disassemble, diagnose and overhaul the valve body then you are going to lose money from the job unless you're an experienced transmission rebuilder. Potentially a lot of money.

If you're going to replace the torque converter then the part is usually $150 - $600 but the labor is huge. Anywhere from 4-14 hours. Especially ugly are transversely mounted, AWD SUVs of the European and Asian varieties...

Full rebuild is usually around $3500 all said and done. Re&Re'ing the tranny with a crate transmission is usually a similar cost.

Trying to diagnose it to find the "Ah-Ha!" cause can easily gobble up 5-10 hours! If you want to check line pressures then the time it takes you to bring a vehicle in, put it on the hoist, access a pressure tap, route the gauge into the vehicle and then go for a road test is a half hour per port at a minimum! Every time you drop the pan is half an hour to an hour. Even doing simple resistance checks can easily be an hour by the time you get your information and gain access. And after this you still have to pay for the actual repair! In the retail world you can't just do whatever you want. You have to be able to explain to the customer why what you want to do is a good usage of their money! And a lot of times that's the most difficult part of diagnosing...


Trying to do any of the easy things is to try and save the customer the cost of a full rebuild or replacement of entire transmission. However everything has a cost. They're also components that come with a replacement transmission. You have a bit of lee-way here if you're getting it rebuilt but if you're getting a replacement transmission after you tried replacing a component then you're paying for that component all over again. Likewise if you try a torque converter only to find out the vehicle needs a new transmission then that's removing the transmission twice!

You have options if you're doing it on your own time but if you're on the clock in a professional retail shop then these are UGLY. You're given a limited amount of time to come up with the best route forward. Keeping in mind that the customer is paying for time and parts. Whether it be diagnosing time or wrenching time.

And this is what makes this profession interesting!

Figuring out where you went wrong it vital. The first step is always admitting that you screwed up, admitting it to yourself and your customer. I appreciate Paul teaching his students this lesson.

The troubleshooting flowcharts are usually drafted by engineers who have never worked on of fixed anything in their life, then they get sent to a tech writer who also has no experience but makes it sound good and look pretty. Engineering students don't learn hands-on skills at university (for the most part in the USA), some countries like Germany have more of a relationship between universities and industry so students get more real world experience. The point is they are not taught how to think about practical troubleshooting techniques.

matt.white wrote: ONE front wheel Noah?! Savage! Haha. At least lift two!!

:whistle:
Yeah, I'm kind of an animal, lol!

I just listened to part two today at work, looks like the test drive would have been key in this diagnosis.
Live and learn, still a great teachable case involving bias voltage on a high side driver, and validating the solenoid with an amperage measurement before replacing the PCM.

I still think these are the lessons where we learn the most, and while it sucks blowing the call, at least the PCM was already in hand and it didn't cost anything to try it out.

All in all a good case study.
Ecwurban raised some excellent points regarding the cost of diagnosing internal transmission faults. With that in mind, I'm curious to see what the next step is for the car.
With all that in mind, plus the age/value of the car, is there any shame in shotgunning a used transmission and converter in this thing? To be perfectly honest, that's probably how I would take it from here.

Excuse my perhaps unorthodox way of thinking but if you applied 12v to the tcc solenoid it should instantly stall the engine shouldn't it?
Never tried it and probably wouldn't just for the hell of it but I'd consider it if I got to the point Paul did. It would have to be in gear I'd assume?
Never done any automatic work so just curious I guess. We just send them out.

Noah wrote: With all that in mind, plus the age/value of the car, is there any shame in shotgunning a used transmission and converter in this thing? To be perfectly honest, that's probably how I would take it from here.

Totally depends on who's doing it and who's paying for it. If this is a FWD then the labor time to Re&Re the trans is 8.2 hours. If it's the AWD then the labor time is 14 hours. That's a lot of time to chance a used transmission. If you could find one that's relatively low miles and the car was written off then I'd say go for it. The problem is that it's such a huge job so that's going to be one of the leading causes of why these vehicles end up in a scrap yard. So you'd be taking a huge chance.

If the vehicle otherwise shifted well without any delayed engagements or slips/flare ups then what I'd do is try just the valve body from a used transmission that doesn't have too many miles on it. It's only 2.5 hours to change so far less risk. If it doesn't change anything then just put the original back in and return it.

Next thing I would do would be to change the torque converter. I would would go new and get one from a transmission parts supplier. Not sure what you have in the US but if in doubt then call up a transmission repair shop and ask them where they source their parts from. They're really not too expensive for a stock converter. Plus if you get one from a transmission parts supplier then there's a good chance you'll get an upgraded unit. A lot of converters have issues with the splines of the clutch assembly stripping out. Unfortunately with this being a transversely mounted drivetrain you're looking at dropping the whole tranny. A lot of longitudinal drivetrains in trucks and vans you can just separate the engine and trans enough to sneak the torque out. Can save you a couple hours. No way you'd be able to do that on one of these guys though.

matt.white wrote: Excuse my perhaps unorthodox way of thinking but if you applied 12v to the tcc solenoid it should instantly stall the engine shouldn't it?

I'd really advise against it. You're far better off monitoring live data while the TCC applies. When the TCC Apply PID changes you should notice an immediate change in the Engine RPM and Engine Load PIDS. Hopefully you have access to a TCC Slip PID or a Input/Turbine Speed RPM PID and can see if the clutch is actually holding. Should have less than 10 RPM difference between Engine RPM and transmission input shaft speed. A good unit will have less than 5 RPM difference.

If you really wanted to manually energize the TCC then don't do it idling. These clutches are not meant to slip. They're paper thin. We're talking only about 0.015-0.020" of friction material between the steels. They're not meant to handle huge torque loads. Not to mention the splines on the clutch. If you really wanted to do this then you'd want to be at least in 2nd and light load cruising on a flat stretch. It'll be a lot more noticeable when it applies but it'll put far less strain on it than idling.

The problem with this approach is it only tells you if the clutch is capable of some amount of application. It wouldn't tell you if the converter is actually good and able to fully lock the turbine to the impeller. A worn clutch would still be able to stall the vehicle if you applied it at idle. Likewise, it'd also still be able to give you a jolt if it were applied in second at low speeds.

Bottom line is you wouldn't learn enough to merit the risk. Trannies are a constant risk/reward juggle.

Yeah I understand what you're saying. I would only have done anything like that after I was convinced the trans was the problem anyway. Not sure why, why inquisitive nature I guess to power it up and see what happens. As someone else mentioned earlier, in my eyes that whole trans is junk anyway.

matt.white wrote: ... As someone else mentioned earlier, in my eyes that whole trans is junk anyway.

That's the way I've been conditioned to view transmission problems over the years.
No body ever showed me how they work, and I haven't had time to figure it out yet.
I admit, at times it seems ignorant to trash a transmission that may just need a solenoid or torque converter. Almost like changing an engine over a collapsed lifter.
But, as previously mentioned, you could end up having that trans in and out multiple times and still end up having to replace it. Hard to make money and keep happy customers that way!

I really appreciate your input on this one ecwurban, thank you!

Noah wrote: I admit, at times it seems ignorant to trash a transmission that may just need a solenoid or torque converter.

Nah, we do it all the time and we're a transmission shop. We've changed many transmissions that probably only had one minor issue. A broken snap ring or a burned up band say. We've practically stopped building GM trannies. Especially the 4L60/4L80E's in their trucks and vans. We can get dealer reman units for stupid cheap. If all we have to do is go through a trans with a basic rebuild kit then we can build one cheap. But if we have to start replacing planetaries or, especially, valve bodies then we're looking at it costing more money to rebuild it ourselves then we could buy a complete dealer reman. And they offer a 3year, 100,000mile warranty. Best part is if anything happens the customer can go to any GM dealership. So you as the installer don't even have to deal with any warranty issues!

Noah wrote: Almost like changing an engine over a collapsed lifter.

It's very much like that. It's a lot of work that can get ugly very quickly. Plus you don't know what else you may find while your in there. Or what if you fix the lifter and the engine still has a knock or tap? They agree to do the lifter because cheaper than a whole new engine but then you find out they still need an engine. You're not going to get paid fully for the work you did on the lifter. Especially if they decide to not go for the engine and just scrap the car. You're going to have to try and scrape out any money you can to pay for your expenses. Otherwise they'll hit you with a, "Nah, you can keep the car." :dry:


It's painful seeing a car leave knowing I'll never get a chance to try and figure out what's wrong with it! :lol:

Thanks so much guys for the great contributions to this thread. Sorry I wasn't able to get inside of this transmission to do the air checks that I mentioned in the video. But honestly after reading #ecwurban posts, I'm kind of glad I wasn't able to
For me, this case study was a win from a standpoint of understanding bias voltage on a power side switched output. I'm not sure I've been able to show it with such clarity in the past. So even though I screwed up on the call initially, I'm super happy with the outcome of this. So many lessons learned for my students on this one.
Bias voltage
Bi-directional control variables
The importance of knowing trouble code setting criteria! (when is it an electrical fault or not)- major screw up on my part here
Just because the "PCM" is one of the options for a fault, does not mean it is always electrical in nature (computer logic in this case)
Measuring solenoid current flow and resistance from the computer connector etc etc.
Thanks again!

ScannerDanner wrote: Sorry I wasn't able to get inside of this transmission to do the air checks that I mentioned in the video.

It wouldn't have been too bad from your perspective. You're at a learning institute and it's a student's car. But if you were on the clock in a retail shop that this would be scary. Air checking the passage ways sounds very simple. But if you're not used to working on trannies you're looking at 2.5-5 hours just to do that. By the time you look up the info, familiarize yourself with it, pull the pan, gain access, make a good rubber tip for an air nozzle, do the tests and put everything back together. And then what happens if you hear a little hissing? Are you going to be comfortable enough calling a valve body? Or are you going to spend more time pulling the valve body and inspecting the valve body to case seals? You're not going to find those seals in stock anywhere so now you're looking at tying up a hoist for a day waiting for parts. Seals come in, you carefully change them, carefully reinstall the valve body, redo the air checks and you still hear a little hissing. Now what? Before you know it you've wasted a day's labor and are really no further ahead. This isn't just a "nightmare, worst case scenario". This is the sorta thing that happens all the time :silly:

I say this video is a HUGE win. Aside from all the other great info in it knowing when to not trust a scantool and confirm the results through other means is such a valuable lesson. I had an early 2000s Dodge Dakota. It was for a used car salesman and he needed the air bag light off. I hooked up my scanner and the code said something along the lines of Passenger Air Bag Switch Circuit. I did all the checks. Switch was working fine. Even got a used ABS module. Could not get that light to go off. Then our shop scanner came back from repair. Hooked it up and the code on that scanner said Passenger Air Bag Switch Illumination Circuit. That's when I realized that the stupid light warning you that the passenger air bag was off had a burnt out bulb. That's what was flagging the code!

As always your work is much appreciated and enjoyable to watch!

ecwurban wrote: I say this video is a HUGE win...

As always your work is much appreciated and enjoyable to watch!

Agreed, the end result doesn't make this any less of an awesome series This and the Subaru injector driver thing are EXACTLY why subscribing is worth it, IMO.

While watching part two, I thought about possibly powering the TCC solenoid with a jumper, and having a low amp probe + scope on the jumper. That way, you could look for the pintle hump in the current pattern, and at least know if the solenoid is moving mechanically (or not). It might answer some questions, but wouldn't prevent you from dropping the pan either way