Code P0741, Transmission Control Clutch

[obis88]

Just had to have my 04 GXP towed away while on vacation here in northern Georgia. The "Service Engine Soon" light came on so I called ONSTAR and they reported a code P0741. Something to do with the transmission control clutch (TCC). Before this came on my car would not go into 1st gear. At a stoplight it would start in 2nd. It was shifting all squirrely and stuff. Finally the light came on. I needed to go up a mountain to get to the log cabin we are staying in. Well it never made it. It died going up a steep hill. Just had the car towed to the nearest Chevy dealership as there is no Pontiac/GMS one nearby. I hope this is nothing too serious as we are on vacation near the town of Blue Ridge, GA and we have a long drive back to the Tampa area. I had a Torrington bearing replaced a couple years back and all new fluid within the past year. Any ideas what this may entail cost wise and has anyone else had this code?

[CMNTMXR57]

Majority of the time, it is a torque converter clutch solenoid. This solenoid controls the hydraulic pressure to both apply and disengage the torque converter. When it is applied/engaged, you should see no (or minimal) TCC slip speed. Essentially the engine is coupled to the transmission on a 1:1 basis. Similar to you fully engaging the clutch on a manual trans.

Anyway, if the PCM commands the TCC on (apply/engage), and it detects a high level of "slip", P0741 is the result. Don't worry though, being a transmission code, it is a "type B" code and shouldn't cause you a fail at your emissions test.

You don't want to know how this needs to be replaced. I'll just tell you to take it to your favorite/most trusted trans shop. It's internal, the trans needs to be dropped, the side cover needs to be removed, and I believe the trans oil pump may need to be removed in order to get access to it.

If not the TCC solenoid, it can also be the turbine shaft seals on the oil pump. But still no easier to fix.

[1fatcat]

I needed to go up a mountain to get to the log cabin we are staying in. Well it never made it. It died going up a steep hill. Just had the car towed to the nearest Chevy dealership as there is no Pontiac/GMS one nearby. I hope this is nothing too serious...

If you mean the engine stalled, it may not be too serious. If you mean the tranny lost all gears, it may be serious.

[obis88]

As I started to go up the hill in 3rd gear it would not downshift at all. Not even when I manually put it into first. As it ran out of steam I gave it a little more gas but nothing. I immediately put it into neutral and coasted back to a turn off road. A Chevy dealership here in Blue Ridge, GA is looking at it now. Just waiting for that call to tell me what they found. I'll post back when I find out. Getting kind of nervous though. It has 108,000 miles but I have always been meticulous on maintenance. And we are on vacation here from Florida. Had the GMC/Pontiac dealership in Florida fax all the previous work done on the tranny to this Chevy so maybe I'll get some kind of warranty protection. Just hoping it isn't too expensive. Would put e real damper on the rest of our summer vacation.

[obis88]

Well nobody at the Chevy dealership in Blue Ridge, GA knew how to fix the P0741 error. The people there said since Chevy did not have a Northstar engine tranny combo like I had they couldn't do anything except get a brand new transaxle! After much debate, I ended up having the car trailored back to Florida for $450. Should arrive Tuesday and the local place here can look at it. I'll update once we see what's wrong. I hope it's nothing serious because I already rebuilt a lot of this tranny 35,000 miles ago.

[1fatcat]

Sorry to hear about your troubles. A major car issue far from home is horrible.

[00Beast]

Impala SS = LS3/4T65 (special, but still a 65)

Bonneville GXP = Northstar/4T80. No Chevy had the Northstar or 4T80E, so the mechanics at Chevrolet only dealers don't know how to work on them.

[1fatcat]

Yep, I was just looking and noticed that so I edited my post.

[1fatcat]

Did you replace the torque converter when you rebuilt it? They can cause this problem in the 4T80. They used a special viscous coupled lock-up clutch inside the converter that nobody can get but the dealer (so I've been told).

[CMNTMXR57]

I think it has more to do with the fact that they don't want to get paid only book time (per GM) when their techs aren't familiar with the unit or it's troubleshooting itself. It's not that they can't troubleshoot it and/or fix it. A P0741 is a P0741 regardless of engine/trans combo. The actual troubleshooting may have some different twists/turns based on which trans it is, but they (any GM dealership) has access to GM Service Information/SI2000, which, selecting 2004, Pontiac, Bonneville, then in the "unit repair" section, enter code P0741. From there it'll probably pull up options for either L36/L67 or LD8. Being an LD8, they'd pick that, and it'd give you everything you need to know about the code, as well as step by step instructions on how to troubleshoot it, and diagnostic aids.

So they could do it, they just don't want someone unfamiliar with it taking extra time that they might not get paid for, working on it.

[obis88]

The torque converter was not replaced before. They said there was nothing wrong with it at the time.

So the car came back to Florida on Tuesday and that afternoon I got the call from the dealership. The torque converter had "blown up" or something and there were metal shavings throughout. The service guy said by the time they added up the cost of new parts it would probably be easier to do a complete transaxle replacement. Cost for everything: $3800. They would have to get it from Lansing, Michigan and it woud take 3 days or so. I decided to call around at other places for other options. Found a place in Tampa that said they could rebuild it for $2500. They guy at the transmission place was a little concerned that this would be the 2nd time I had the transmission fixed. He said the 4T80 tranny is very strong and he hasn't rebuilt very many at all in his 30 yrs in the business. I'm having the rear main seal checked while they're fixing it. I'll post here what all they find and how bad everything was. I'm really debating whether to keep the car after she's fixed. It was a lot of fun the first 3 1/2 yrs but it's becoming more and more costly as with any car I guess. She is just so good looking and has so many nice features. But every time something goes, it's to the garage. I do my own oil changes, brakes, and simple things but big things and electronic issues are things I can't do. Wish I could afford a new CTS-V!!!

[00Beast]

That is exactly why most transmission shops install re-manufactured Torque Converters during a rebuild, whether it was needed or not.

[CMNTMXR57]

SH*t for $3,600 you could get this "built" one. Granted of course you'd need a torque converter, but you no longer would have any transmission worries.

http://www.importperformancetrans.com/i ... ail&p=4310

[CMNTMXR57]

WTF is going on with this site. It takes 20 minutes to make a simple post, then doubles them!!!

[obis88]

So, my car was finally fixed. It was indeed the torque converter. Had to replace the transmission mount, motor mount, and did the rear main seal as well of course the rebuilt tranny. Total cost with everything including tax was $3400. This included some heavy duty part that I can't remember. Everything is fine except for a vibration that starts at about 1200 RPM and goes to about 1800 RPM. The repair guy took a drive with me and noticed it as well. He thinks it may be the new tranny and motor mount. So he loosened them up a bit until they can seat in better. He did this 3 days ago and I still have the vibration. It occurs whether you rev the car in neutral or it's in gear. Always between the 1200-1800 RPM level. After that it goes away. Problem is, there are many times the car will be cruising right within that RPM window so I feel it a lot. It's not a really rough vibration but definitely noticeable. Any thoughts on what this might be??

[1fatcat]

Out of balance torque converter? Test by removing the torque converter bolts and run the engine, see if it still vibrates.

[CMNTMXR57]

He beat me to it.