6L80 Electrical and Hydraulics
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- เผยแพร่เมื่อ 26 ก.ย. 2020
- This video covers the electrical and hydraulic operation of the GM 6L80/90 RWD transmission used in many Chevrolet and GMC RWD and 4WD vehicles. These transmissions are still offered in 2020 models and arrived on the scene in about 2007. In this video, I cover the the Transmission Electro Hydraulic Control Module (TEHCM), the pressure switches, the hydraulic valves and I cover the changes that the TransGo shift kit does to the operation of the hydraulics. This video is intended to teach a student or a technician that's new to automatic transmissions the electrical and hydraulic operation of this transmission. This is part of the SIU Automatic Transmissions Curriculum, which can be found at:
www.automotivetextbook.com/au...
Go to that site to view other videos on this and other transmissions, such as the FCA 41TE, Ford 6F50, GM 6T70, GM 4L60e, ZF 9HP48, GM 6L80, and Jatco CVT. - ยานยนต์และพาหนะ
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I watched your power flow video before this and even posted how nice it would be to see some information on the hydraulic system. Well lo and behold…….. I am going to continue to study until this makes more sense. I am a thirty (+) year Master Tech that has just recently decided to get into transmission repair/rebuild as aggressively as possible. Like most of the systems I have learned over the years, knowing the “theory of operation” (what does this part/system do and why) is key when not only diagnosing difficult issues, but also being able to see/verify proper assembly and operation. I don’t want to simply just replace what I think I should or what I’m told I should during a rebuild and then just assume the unit will work properly. I want to know as much about why and what as I can learn. I would love to build a couple of transmissions with you as an instructor!!! Thanks for making the videos. They really are helpful!!
Fantastic video on theory of operation. Really helps with diagnostic for a guy like me who is in the repair field but not necessarily the transmission repair side of things.
very helpful video... torque converter failure, 3-5rc rv was sticking and CSV#3 was as well... this explain why i had a delay in the 4th to 5th shift
Thanks buddy! This is probably the best learning tool on the 6l80 i have found.
You’re welcome!
This is full of really good 6L80 theory and info - thanks for laying it out.
No problem! Glad it helped!
Many thanks.
Here is what I find interesting about the 6L80 and 90. There is only one one-way clutch for first gear, which means that by default there should be engine braking in all other 5 forward gears. So am I right to assume, that when coasting, the TCM drops the converter feed pressure to a minimum, and if necessary, disengages the TCC, for maximum slippage, reminiscent to what it would be pressing the clutch on a manual? Likewise if the brakes are applied, that feed pressure would be immediately ramped up?
If that is true, then the next question is, in an emergency braking - will it re-apply the TCC and the low/reverse clutch when it gets down to first gear?
Thanks for the awesome video! I wish I would have found this before I rebuilt my transmission. TCC failed on mine, and destroyed the pump. I did a complete rebuild and replaced the pump. Everything works great except for when it gets up to temperature, and only intermittently, I’ll get 3 - 4 pulses immediately after shifting into 2nd. It only does it occasionally, and only when it’s hot, so strange. I’ll have to rewatch your video a few times, and maybe I’ll have an epiphany. Thanks for the awesome content!
I wonder if you are leaking 2-6 clutch oil. That passes through the bridge seal between the center support and valve body. Sometimes that seal has a hard time surviving. Seal aftermarket makes a kit that locks the center support to the case and provides a better seal.
@@siuautomotive Thanks for the feedback! When I did the rebuild, I installed the Sonnax seal support kit for the center support seal. I pulled the valve body to check the center support seal anyway, and it seemed fine to me. I decided to air test everything since I had the valve body out, and discovered that the 1234 circuit was severely leaking into the 35R, and compensator feed circuits. You’ve probably already guessed where this is going. I replaced the pump, and forgot to install the expander rings that go under the pump sealing rings. I looked back through the ATSM manual and didn’t see any mention of them, but maybe I’m just over looking them. Your 6l80 rebuild video was very helpful in confirming my mistake. How this thing shifted at all baffles me. I installed new seals with the expander rings, and it shifts beautifully now. Thanks for your help!
@@cfamgang the ATSG manual only shows the early stator sealing rings that did not utilize the expander o-rings. They are only used with the later non-rotating sealing rings. It almost got me as well.
Muy interesante contenido y muy agradecido
Soy latino del sur de América (Colombia )
Sería muy importante suptitulos en español
Very good info
Slightly off subject, GM Colorado 2014 6L40 does not engage Drive first gear and slips, but does engage if put in Manual first, where should I look please. No codes. Awesome video, THUMBS UP
this good learn
Thanks for the video, does the TEHCM have pressure sensor to send the info to the scan tool or is it mechanical gauge test only?
Very very helpful video, what would cause slip once its selected a gear say 2nd or 3rd, moderate to heavy throttle input, is fine under say 50% but anything over that it begins slipping, been trying to work out whether maybe the pressure isnt anough to hold the clutches engaged, any advice or pointing in the right direction would be appreciated
Well explain and seems your are automatic transmission specialist
In the TCM TCC Desired Pressure tune I see it refers to PCA Pressure. Does anyone know what PCA Pressure is? I suspect it’s not the same at PCS Pressure.
Rebuld a 6l80 and in neutral range the truck moves in reverse slowly help please
I could really use your help ! I have a brand new GM 6L80 and it will not shift out of first gear. Goes into neutral or maybe slip until you let off the throttle then 1st gear returns. Tcm is commanding the shift but nothing is happening. What should I be looking at ? Also has a 2-3 second delay going into reverse.
Where do find this interesant your information, to my, ilustracion learn it?
Where can I get the fluid diagrams?
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I have a 2008 Escalade with a 6L80e that is having EXTREMELY harsh 4-5 shift under any load. Other than that, there is no slipping, flares, or anything. Logging shows no errors, and there are no codes. Does this sound symptomatic of a TECHM/valvebody issue, or more likely the transmission itself? Fluid is at proper level and not burnt, trans never gets above 145F. It's odd that only the 4-5 shift is affected and it's such a harsh shift that it wobbles the truck.
Well, I would be wondering if the 1234 clutch is hanging on too long, sine that's what's releasing and the 3/5/R is coming on during the shift. I would suspect you'd have issues with 3rd, 5th, and Reverse if it was the 3/5/R. There is a "balance" end of the 1234 piston. I just wonder if you are having issues with that. The spring and compensator (balance) oil are responsible for pushing the piston back when released. The solenoids aren't serviceable so if you don't find anything internal, you'll have to try a new TECHM. You could check for checkballs that shrunk (common) and for any worn valves. Since you use the term "logging" it makes me wonder if you are using HP Tuners. Did anyone tune this trans? Maybe they monkeyed with something that could cause this issue?
@@siuautomotive I am going to try a new techm/Valvebody assembly first to avoid pulling the trans. I have efilive for ecu tuning but no trans mods, just using it for logging ability.
Hello, I am talented in repairing automatic gearboxes and car maintenance, and I am now looking for a job. Can you hire me
Hello boss
Dang I’m seeing 300 psi on 1st and second when shifting but then settles to 150. And she’s whinny so sure got a leak somewhere
I wonder if it’s the bridge seal between the case and the 2-6 clutch housing. Those seals can blow causing a big leak. Seal aftermarket has a fix for that.
@@siuautomotive Thank you for responding though I love yalls videos I hope to learn more from y’all in the future and I will look into what you commented .
@@siuautomotive so I went and seen what you meant by bridge seal and I do have the sonnax center support seal those little metal inserts plus the rubber seal but that always worries me when I put the valve body in that it’s not sealed . I have some new transgo valves coming for this new lower valve body I installed so I’ll get a chance to test that theory .
The devils own design. Outrageously over engineered. Frightening just to look at. Better to take the bus.