So OP asked for an expert. How many that answered are?

The thermostat on the cooler lines is not a fix for anything. It's a part we're supposed to replace with ANY transmission repair. GM's new design has a lower opening point.

That being said, the 6L family has pump problems caused by bad converter clutches and a dumb way they program converter clutch operation.

P2700 is not a valid code and neither is P2011 nor is P22534 (too many numbers). So I can't help with the codes. TCM won't help if it's not programmed to the vehicle and is not the likely cause. If your 6L is dead the normal way, you'd be able to smell the fluid on the dipstick from the next county.

Kenny Wilson is good people. Obviously I would recommend me first but he runs a tight ship.

I have a 2021 6L90E fixed and ready to test drive when I get to work. It merely broke the ring gear off the output shaft and wouldn't go. First one I've seen.

Can you explain this further; this is replaced with any transmission repair? As I stated, I had a similar issue. I was getting the warning light when pulling my single axle trailer while hauling my Ranger. I believe it was coming on at about 275-280 °. My dealership recommended changing the thermostat and a fluid/filter change. This was at 59k miles. It did fix my issue.

Hang on, let me edit and ask this after I just now found a service bulletin: Why was I charged for this if they had to do a redesign? I read the service bulletin and now understand your explanation, but it seems that I should have not been charged. It was $600.00 which included fluid and filter change.

Sorry...Codes were P0700, P0711 and P2534. These were hand written on my ticket at the dealer in Pampa. We have a way to program the TCM. Please advise further.

700 sets in the ECM when the TCM has an issue. It's nothing more than an EPA flag.

P0711 is for the fluid temperature sensor. Common issue with 8-speeds, not 6L's.

P2534 is a low voltage code. Maybe...just maybe you dodged a bullet.


Just because a new design is produced doesn't mean it's free. I am not sure I understand your point.

If they had to redesign, that is an admission that originally it had a design flaw and the vehicle wouldn’t perform. The service bulletin states that the redesign opens to cool at 140 degrees rather than the originally designed thermostat that opened at 190. The same vehicle had a service bulletin on the lifters that failed at about 30k miles. That was a covered repair.

At 30K, the lifters were likely still under power train warranty. See below.

The thermostatic element in the fluid cooler pipes is not a repair any more than a fluid and filter change. It's supposed to be replaced any time a REPAIR is made to the transmission on any vehicle called out in the Technical Service Bulletin (TSB).

A TSB is nothing more than information to a new or corrected repair ... an update. It implies no coverage whatsoever unless explicitly expressed therein.

You may be confusing a TSB with a special policy, special coverage, or a recall. They are all different.

19-NA-219 is information only. No coverage implied (lifters).
PIP4568S is information only. No coverage implied (lifters)...and a PI (Preliminary Information) is a level below a TSB.

If you know the number of the TSB regarding lifters (off topic), I can look at it and do a better job of explaining the difference.

I am not aware (off the top of my head but there's a lot jumping around in my head) of a special coverage (not a TSB) for lifters although they were failure prone (in four different manners depending on year/generation).

Just because a manufacturer has developed a new procedure or part does not mean everyone gets it free. If that were the case, the '68 SS396 Chevelle I drove in high school (early '90's) would have gotten a few new parts from the local Chevy dealer free.

Read this before you let anyone put the same torque converter (JMBX from GM) back in on a rebuild. Youtube it too (JMBX converter or 6l80 6l90 problems), there's a lot of confirmation out there.

https://www.sonnax.com/tech_resourc...n-updated-converter-in-your-next-rebuild

Their converters are a plague and a new one only kicks the can down the road. I know, I'm on my third trans/converter replacement now. Mine were both under warranty so I had no say about what got put back in. Each time the woven clutch material gave up and contaminated the transmission to death.

Another thing, make sure the GM service bulletin gets taken care of, it removes the 195 degree trans cooler thermostat and replaces it with a 147 degree version. Myself, I bought a kit for 40 dollars that eliminates the stat all together (30 minute install), and added a supplemental cooler. GM's reasoning for using a 195 stat is to keep fluid viscosity down, improving mpg by a few tenths. Of course you pay the price elsewhere while they get the rating they need. I about lost my sh1t when I learned they were keeping the transmission that hot on purpose.

I hope yours is an easier/cheaper fix, but I fear you're in for a replacement. Just for god's sake, don't let GM/Chevy put all the same crap back in there, have it done right.

Hackler Transmission in Carrollton quoted me $4,300 earlier this year to pull mine, correct everything, rebuild, reinstall and program it. I just haven't gotten it over to them yet.

Well, pulled the pan this afternoon and it was nice and sparkly. Went ahead and pulled it, I’ll get it replaced this week. Thanks everyone for the help!

Thats too bad.
Oh well, make sure you get a billet-torque-converter on your replacement, or you'll be right back here in a jiffy same issue.

As I stated, it was necessary to change the design. Originally designed to open at 190°, the truck would not perform to specification. A redesigned thermostat was necessary so that the transmission would not overheat. SB# is 21-NA-199, check it out.

That's not the bulletin for the lifters like I asked.

The truck was operating in spec and still is. It was necessary to change the design because the spec changed. Still don't understand why a small percentage think that a redesign implies no charge.

If your transmission was going to fail before the update, it still will. You did not get a repair, you got an update. Temperature is not what kills the 6L, it's the converter clutch coming apart and scoring the pump that does. And a billet converter is not a magic fix. Billet just means the housing was machined from a solid piece of metal ... or at least the clutch face was. GM is not building replacement converters the same as the originals. They updated the design. I guess that means GM should pay for all the out of warranty 6L's. I myself would choose an aftermarket converter made by a company known for heavy duty and/or performance converters, billet or not.

How can you say it was operating to spec when I got a warning light telling me to stop moving and let engine idle? It wouldn't pull a trailer, way under load limit. Had they not redesigned the thermostat to open at a lower temperature it would continue to over heat and I would continue to have to pull over every 100 or so miles. That doesn't sound like performing to spec's to me.

I thought you would be interested to read the SB I provided that shows the change they made to the opening temperature on the thermostat. I'm wondering what prompted the change. Could it be that GM was getting reports that owners couldn't pull trailers as the trucks spec's stated?

Ok I have a 2018 1500 Silverado 6L80E. Does it have the sh!tty converter too?

A little late to the party but the Chev truck we used at my parts house job went the way you described. I was able to limp it from downtown Dallas back to Terrell in a lower range (didn't have any gear up from 2nd). Turned out the wiring harness to the transmission had rubbed through causing the issues. Kinney's transmission in Terrell did the work.

Yes, my advice is to get the converter swapped out asap. It's not "if", but "when" it fails and takes the whole transmission with it.

I build transmissions for a living. I built a 6L80e today-just for reference. I build these units-both the 6L80E and 6L90E transmissions pretty much every day of the week. They are the #1 seller for the past few years.

I did not read every post above, but some that I did read... let's just say there is some misinformation active in this post.

For the record, my shop charges $3250 DRIVE OUT cost, tax included, on a full rebuild, including new torque converter, and TEHCM, and we offer as standard a 5 year 100,000 mile warranty. We do NOT use GM torque converters. Ever. For any reason... except maybe as a door stop.

The torque converters, paired with the programming inside the TEHCM, is 99% of the time the problems with these units. I can count on one hand the # of broken 6L's that have come through my shop in the last 5 years that failed for any other reason.... it's *almost* always torque converter failure, or damage to the unit from metal coming out of the torque converter--pressure control solenoid codes are NOT solenoid problems... it's usually the pressure blisters are damaged, or valves in the valve body are stuck due to metal from the converter plugging up the valves.

As part of our standard rebuild we also bypass the thermostat (in those vehicles that are equipped with the thermostatic block from the factory). Your transmission will run significantly cooler than it did from the factory if it was equipped with a thermostatic block from GM.

As part of our standard rebuild we re-program (tune) the TEHCM to fix the GM programming which leads to damaged torque converters in the first place. No more constant slipping of the torque converters in 2nd through 6th gear. Good solid, firm, TCC lock up.

As part of our standard rebuild we use Precision Billet Torque converters which are known to be better machined and have a perfectly flat surface inside that the converter clutch rides on. This stops the heat blisters that occur inside the GM torque converters that then shreds the lock up clutch, and causes the entire unit to be taken out.

As part of our standard rebuild we utilize BOTH Trans-Go shift correction packages that address MANY of the valve-train, and pump pressure control valve, issues.

For those wondering what a TEHCM is---Transmission Electrical Hydraulic Control Module-- it is the TCM or COMPUTER that is paired with the solenoid pack that is bolted to the valve body assembly. It is the brain of the operation as it relates to transmission control.

If anyone needs help, we are just a phone call away. We answer our phones from 8AM Until 9PM CST. We are located in Houston. Our turn around time is typically next business day-2nd day when we are really busy. We build these units and keep them in stock because they sell as fast as we can assemble them. Call us 713-859-7159.