dwchapmanjr

Yes, 6.2 as well. GM/Chevy Protection plan just approved a new temp sensor. Dealer read a -48F on it. They're checking thermostat now so at the least the temp sensor is bad but approved under warranty. Interesting, I had to look up road master. I have Magnetic Ride Control, wonder how it would play with it. I thought I'd be doing some towing by now but haven't yet.

I'd ask to see them. Picoscope should hopefully be fairly clear as to the source of the vibrations or classification of it. (Is it aligned with tires, prop shaft or engine rpm and which order). Its rarely used and voided so they may not be too familiar with it. Sounds like electrical or BCM related but yes after a battery dies or truck loses power it will have quite a few codes and may ride differently for a while as it needs to relearn some of the drive characteristics. I'd expect most of the codes to be "communication lost" codes with the BCM since many systems connect to BCM. Engine hour cleared out is a common issue when power is lost as that's stored in the instrument cluster control module and doesn't always persist loss of power.

Have them run a picoscope on it to confirm the source of the issue. Sounds like they're just taking stabs in the dark on the usual suspects.

Shudder under light acceleration at 1100-1300RPM sounds like the TCC shudder issue on the 2015-2017's (I've had it for a few years before the new fluid finally fixed it). Has anyone had the dealer run a picoscope on it to find the source?

Would not surprise me. This is on an 8L90 which is known for its temp sensor issues. Its part of the wiring harness in the transmission pan. If I have the single piece harness the valve body has to get removed too but I think its a two piece. A bit more than I want to get involved with since I have a GM Protection plan. I can do some basic mechanical stuff but want to waive voiding the warranty and generally not comfortable dropping the pan on a transmission. But I can plug in a scan tool and read codes and freeze frames like nobody's business! Freeze frame on it has shown a failure 3 out of 11 times, 7 passes and one canceled test. The thermostat isn't opening so the issue may be that the sensor is not very accurate at the lower temps or it could be starting to flake out. When its a cold start in the morning, the fluid sensor does read within 10F of ambient temp and close to coolant temp. I took a few years of advanced chemistry in higshcool and college and I don't ever recall using the term substrate.

No, that's exactly what I'm looking for! Human readable terms for the condition. Interesting, so that would imply there is a temp sensor somewhere other than the fluid? I ended up finding a freeze frame on the code which was helpful and showed a TFT temp of around 48F which likely meets condition 3 as I imagine it dipped while driving. In any case, thanks for sharing the DTCDECODE, I don't know why I couldn't find that before. I still don't understand the charge of the "axis and curve" tables but now I don't have to.

From your persistence, I decided to fiddle with my scan tool a bit more and it captured a freeze frame on the most recent event. It detected transmission temp at 48.2F and its the 3rd time out of the past 11 test cycles. 7 successes and 1 instance where no test was done(assuming aborted due to operating conditions). Entirely possible it could be sensor or thermostat or both at this point. Should be interesting to see what the dealer determines/finds. I'm just hoping its a 2 piece harness being a 2015 which makes for an easier repair. Not that I have to do the work but the less parts come off the less possibility for mistake since valve body has to come off on the 1 piece.

Yes seems accurate and transmisson temps are in line with people who have done the thermostat delete. I have gm protection plan with $100 deductible so that's all I should be out of pocket.

Funny part is I just got used to the shifting. I really think my thermostat is just broken/stuck open though. Monday I got both codes which caused MIL, Tuesday a single instance of P0711 and then nothing since. I get readings from the sensor so its returning data that seems normal. Its highly variable but I think that's because the thermostat isn't closed and allowing it to warm up properly. I thought this was a sensor or harness issue since most all P0711's seem to lead there but I think my case might be different. Have an appointment Monday with my findings and let them figure out what to do with it. What makes you think its the harness?

I paid $3700 for 5 year 60k miles on my 2015 Yukon since my powertrain just expired but I hope to keep it for another 5 years. Stuff on it is expensive to repair/replace.

You could try a local shop to do these. This isn't a dealer only item, you could even purchase a GM MDI and then pay for the 3 day ACDELCO TIS2WEB subscription ($57 last time I checked) and update your own calibration and firmware and do fast relearn. In my home town I found someone that invested in a GM MDI and they can read and check calibrations like the dealer can. The GM MDI 2 is like $900 though and be careful of the older GM MDI, there are many clones, some good, some bad. My Foxwell scanner will do some of the relearns and resets and it was only $150ish.

Not surprising. What year? 2016's have the 10yr/150k mile replacement on the harness because they went from a 2 piece to 1 piece and I guess it had defects in it What's it doing? Mine occasionally glitches like a loose cable. It does this for 1 second but its done this since about 3k miles and I'm at 38k miles. Yeah I'm having a little buyers remorse at some of the things going out on mine. I went through the TCC shudder issue for a few years although the new fluid has helped. I've had my TCC replaced early on in the 5337 TSB days when it recommended it. I went through a round of magnetic shocks and still have drive issues that seem like I did nothing.

Well "not calibrated to this cooler tranny temp" may not be the right way to think of it. I imagine it has a sliding scale of pressures at various temps but it has better tunings and applies more appropriate pressures at the temp it has been optimized for (around 195F). At 160 its going to operate but with harsher shifts. I'm guessing it may not even use the shift adapts its learned at lower temps and just use the pre-set factory shift adapts at lower temps. I plan on getting my thermostat fixed, I will let you know if it helps, although every time I take it in they do a fast relearn on it which usually fixes all my shift concerns for about 5 months. I drive so little and short trips I think my shift adapts just learn bad or don't learn all the clutches properly. Mine is a 2015 Yukon just breaking 38k miles. Was your question about P0711 because you flipped it and got P0711 or just read about P0711? P0711 is usually triggered by a faulty or failed temperature sensor which is in the pan and connected to valve body. 2016 has a special coverage for 10 years , 150k miles on bad sensors because they apparently had a different "upgraded" design that was more prone to failure.

Interestingly enough mine threw P0711 and then P0700 (which is what sets MIL when P0711 happens twice). I figured it was the failing temp sensor so I monitored with my dash gauge and scan tool and my temp sensor seems fine but what I noticed is my thermostat seems stuck open and it takes forever to warm up. The conditions for when P0711 triggers are confusing but I did post this "question" on another forum - From what am reading, P0711 is likely throwing a code because the ratio of temps is out of line. Maybe the collant temp warms up to 180-200 but the transmission is too cold and it expects it to be higher. In any case, what's failed to be mentioned with this delete mod is that the TCM is calibrated for the higher temps and it shifts better at them which is why the thermostat is there in the first place. Its a performance and mileage thing. I don't believe the TCC will even lock up until around 70F. It wants 195F for smoother shifts.

Resurrecting the dead. I had a P0711 earlier in the week with a P0700 (this caused the dash MIL). Cleared it and only P0711 came back which doesn't cause the MIL. Did they replace the temp sensor based on P0711 alone? For P0700 and the dash check engine light to happen P0711 has to trigger two drive cycles. What I did notice is my thermostat seems to be stuck open as transmission never gets up to temp like it used to. Thermostat opens at about 192F I believe. More related to this topic, I'm nearly 2 years out on my flush with the "new" fluid and no shudder but I do have rough shifts that I believe may be related to temperature or temp sensor.

Earlier in the week my check engine light came on and I saw the P0700 and P0711 which lead me to Transmission Fluid Sensor issues and people having to replace them. I started monitoring the sensor and noticed it didn't fail like most other people but it takes an awful long time to warm up only peaking at 150F whereas previously it seemed to always be near 200. It took about 45 minutes of driving to get into the 140's and only passed 150F after another hour of driving after that. As I learned the thermostat is only supposed to open up at 192F so I believe mine is stuck open. I will see if the dealer will give this under warranty but I'm curious, anyone do thermostat deletes and regret it? From what I read, the TCM wants 200F or close to it for better shifts and this is why the thermostat is there in the first place. On the other hand, living in a warmer climate where it doesn't usually get below 40-50F, could leaving this thermostat open extend the transmission life?

I did find this on an unrelated but GM vehicle but I don't understand the terminology. What is the TCM substrate temp and what is the power up temp? Are there other temp sensors on the transmission?

For what its worth, my Foxwell NT510 Elite did seem to be reading a wrong value. They sent me an updated fix and I see temps now so I'll graph it.

Interesting way to test. I will leave it to the dealer as I have a GM Protection Plan and hoping this is covered. Upvoted your answer, thanks for the info. If anyone else knows how to read that chart though I'm still interested in learning that.

I am sure the sensor is flaking but my my only hesitation on the open is maybe my scan tool is trying to read a wrong value because the dash is getting a value from something. Other people that have had the fluid sensor go out say the dash acts up or stays at 100. More just curious to understand the conditions from the tables. Any ideas on how to apply the 2d table to the conditions?

I got the dreaded P0700 & P0711 on Monday on a 2015 GMC Yukon Denali. Cleared the code and it came back. MIL hasn't iluminated yet so I'm waiting on another drive cycle before I schedule an appointment with the dealer. In the meantime I wanted to understand the conditions of P0711. GM has a great PDF but I can't quite understand it. https://gsi.ext.gm.com/gmspo/mode6/pdf/2015/15OBDG08A Transmission Diagnostics.pdf I don't quite understand how to apply the table to the conditions. Further to add confusion, my scan tool is reading -40F for TFT although in tow mode my transmission temp reading hovers between 125 and 150. I did watch it once and see it dip to 100 flat from 125-150 for a brief moment so I imagine its just a flaky sensor but I'm more curious about what triggers this based on those conditions.

Tire replaced but issue still happens. Interestingly I found this on TSB 16-NA-339 - Condition 6 - "Rough, Harsh, Stiff Ride Concern; Z95 MR Suspension (most noticeable 35-55 mph (56-89 km/h) on relatively smooth roads with minor road input)" Its a bit confusing but seems like some "shock characteristics" go to the default while learning and then "learn" bad and lock that in. I wonder if there's a way to reset that.

Looks like we have similar issues but my mileage and driving pattern is different. I hit 38k and went through my first one that warranty wouldn't cover. Eventually had to replace all 4. I don't have the side to side but I feel every road vibration. My passengers don't so I wonder if I am just more sensitive or it is only happening on driver side. Did you every find a fix?

I might be bringing this thread from the dead, or not but same issue for me, 2015 Yukon Denali, 38k miles. January of this year I got bad news that one strut was bad while at the dealer for oil change. I needed new tires as well. COVID hit and I stopped driving it for weeks on end except for a daily test. Around July I got to thinking if one strut went out, other shocks/struts might be because I started having rough ride issues. Checked the rears and they were both leaking into the bladder and eating through it so I replaced those. Ride was a little better but not back to normal so I checked the remaining front and it was leaking so I replaced that as well. Took it to the dealer and they couldn't find anything and claimed they couldn't reproduce it but road force balanced and rotated. I drove off the lot to find I had a tire with conicity in the rear that was in the front now causing a pull. I hoped replacing that would fix the ride issue but it didn't. My passengers don't seem to feel it so its likely on the driver side. Might just be the tires, its too low mileage for much else to be wrong unless it needs the new strut assembly. There is a TSB which states that, replacing rear shocks and full front strut assemblies and shocks but I've heard mixed reviews as to whether it fixes it.

Last post on this but as I was draining I noticed my reservoir tank was a little wobbly. I'm guessing when the battery was replaced it wasn't properly secured. Seemed like it wasn't flush against wall so I retightened it. I imagine over time that wobble could lead to premature cracking. It still has some give but no wobble. I imagine the give it has is just a factor of how little securing it has. It just sits on a clip on the side wall and two bolts in opposite corners.