cleanfreak

Hi Jim- Do you happen to know the TSB # for the exhaust replacement? I was told back in July of 2015 that the exhaust TSB would be released in October, that is October of 2015. Fast forward almost a year later with me checking every 2 months with the dealership to see if the Exhaust TSB has been released (to no avail) and this is the first mention of anyone actually having the work completed. Many thanks.

It was actually was a bad faulty cable that connected to the Display. They installed a new cable and I have not had any issues since.

My 2015 Yukon has been in the shop for over a week for the 'blank' screen issue. The first thing they did was the firmware update. All was said to be fixed and working. Two days later, when we went to pick up the vehicle up , the technician was driving the vehicle around to us and noticed the screen was blank again. The 2nd thing GM informs the tech to do is to check the connection between the HMI module and the screen. If the connections are good, then they are informed to order a new screen. The new screen arrived and was installed and we were told all is good and that they checked it twice with no issues. Today, they had the vehicle already pulled around waiting on me when I got there. Guess what? I get in the vehicle, start the vehicle......and still have a blank screen. The service manager sees me waving my hands in the air in frustration and comes to find it still not working. ........note, when pressing the screen, the stations will change, etc. but it is just blank....... I will assume the next step is to replace the HMI module itself, but from my research, it looks like those are not to stable either......... The service manager stated he was not for sure of the next step and we are awaiting direction from GM. I have truly come to regret purchasing this vehicle. Next month marks 1 year of ownership of this truck, with a total of 2 months of repair time in the shop.

For me, Yes. This has corrected my issue, or at least corrected it to where I can no longer hear or feel the vibration or buffeting...... However, My wife just text me and stated now there is a 'click' in the steering wheel when turning left or right. It does not do it while parked and turning the wheel.......It did not do this before the repair. I am now at my wits end....will the issues ever stop coming?!?!

***UPDATE*** The replacement flanged arrived on Tuesday, but was the incorrect flange for my vehicle. GM sent another one overnight and the dealer replaced on Wednesday. I received a call from my SM stating all was repaired and he gave me the new picoscope readings which were drastically better than the first readings. I was on my way on vacation when I received the call, so I did not get a chance to drive the vehicle until today. I am happy to report this flange replacement has fixed my vibration issue at 53 MPH and I do not hear any buffeting at 43 MPH. GM also will be giving me an extended warranty of misc items from 36K to 100K for my troubles. I have to say, I am happy with the result and with GM's offer. I will report back if the issues return, but for now, I am happy with the results. ....Now waiting for the V4-V8 exhaust fix to be released in October.......

***UPDATE*** My dealer has now had my vehicle another full week. As I stated in my previous post, my issue was supposed to be escalated to a specific engineer and that the next step was to get an entire new rear end housing. Needless to say, after a week, this did not happen. My Service Manager (SM) told me GM required him to do a multitude of test with a Pico scope (basically a device that measures vibrations). During the test they found the following results: The worst of the vibrations were at 53 MPH and the vibrations measured 29.7hz with a 49ng at that speed. The Pico scope also reported the vibration was coming from the driveshaft. They measured the driveshaft to the ‘nth’ degree and did not find anything unusual. Then they focused on the head end connection and the rear end connection of the driveshaft. They did several measurements and found the rear pinion flange to be warped. It was measuring .27mm at the top and .47mm when rotated (I am not 100% for sure what this means, but I assume it should be the same measurement). My SM stated the pinion flange looks to be cast incorrectly causing the flaw in the design. Basically, all of the testing took a full week and a new pinion flange was ordered on Friday and arrived yesterday afternoon. If everything goes as planned, including more test after the new pinion flange is installed, I should be able to test drive the vehicle this afternoon to see of this corrected my problem. I hope this solves both the vibration at 53 MPH and the buffeting at 43 MPH. I will report back at let you know my findings.

I do not. They should be able to look up the # in their system and print a 2-3 page document with pictures to show them how to repair. I saw the document, but I did not get a copy of it.

@jason-Thanks. You are correct, it is a mess and my patience is running thin........I still have a slimmer of hope...... ***UPDATE*** I have some information that might be useful to some. First, I found out (sort of) what the mysterious "muffler fix" is. It is actually a fix that is not available yet. When the vehicle changes from v8 mode to v4 mode there is a 'stutter' or short vibration during the transition. GM is well aware of this issue and they are working on a solution. The solution has to do with the muffler and the exhaust system. GM will be providing the new exhaust system in the estimated time frame of Sept-Oct. For what it is worth, my vehicle does have this ‘stutter’ transition issue, but it is not very bad. However, it is a major issue for the 2015 Tahoe I have for a rental vehicle. To me, it is funny how some vehicles experience various degrees of the same issue. ***Please note this has nothing to do with the buffeting issue, or vibration issue at 53 MPH*** I am not for sure if this has been made known or not, but a new Technical Bulletin (PIT5429) was released on June 1st to deal with “vibrations” or “Rough Harsh Ride” for Yukon Denali, Cadillac Escalade, and Tahoe LTZ, Suburban LTZ models built before 2/10/2015. These models have the Magnetic ride control Suspension (RPO Z95). My vehicle is not equipped with this, but it might be useful for someone. Please see attachment for the bulletin. PIT5429.pdf PIT5429.pdf PIT5429.pdf PIT5429.pdf

No. The rear end is not fixed. When they replaced the ring and pinion and set the backlash at .07", I believe the "buffeting" (sound only, no vibration associated with this sound) at 43MPH was gone. However, something was not set just right causing a new 'buffeting" sound that is directly associated with a new vibration that is most present at 53 MPH per my post above. In order for the dealer to be reimbursed by GM for the work they do on the vehicle, they must "go by the book". This 'book' is a laundry list of items to troubleshoot. The first item on the list is the headliner fix. Items on the list (in no particular order) are: Headliner TSB replace tires "muffler fix" Backlash testing a. Ring and Pinion b. New Chunk c. New Housing Since I assumed the tires and muffler fix was not the problem based on information I received from the Service Manager in Michigan, and provided proof (via the actual work order), they skipped the first few listed and went to the backlash testing. Speaking of which, I have a new update..... ***UPDATE*** I went to the dealership and test drove my vehicle on Friday. Due to the vibration at 53 MPH, they replaced the chunk in the rear end. They also repaired all of the rattles and figured out what the "liquid" substance was coming from the rear view mirror housing (there is a new bullentin out for this housing leak). After driving just 2 miles I quickly notice the vibration was still present and the replacement of the chunk did not resolve my issue. I drove the vehicle back and had a long conversation with my Service Manager. He stated they also reset the backlash at .04 after talking with a GM technical advisor. He showed me the documents that are produced stating what the backlash is/was to be set at and it showed .05 - .07. After talking with the GM technical advisor, the advisor stated this information needed to be updated and told him to set it at .04. Either way, the vibration was still there. He stated that since this did not solve my issue, the next step is to escalate the issue to a specfic engineer that will be in charge of my case and it will be given a case #. He stated the next step is to replace the housing altogether, which he is ordering today as long as the enigineer gives him the 'OK'. I now have a myriad of questions and thoughts going thru my head..... Did the vibration always exist, but was only noticeable when the changed the backlash setting? Is this truly what is causing the buffeting? Does this mysterious 'muffler' fix need to be done along with the other fix to be fully corrected? I will have another update as soon as I have something to report.

TSB # 3743752 will fix your issues as long as they do the all the work and install all the components per the bulletin. It is a simple fix once thay have all the parts in hand.

I am not 100% for sure. My Service Manager mentioned he would do the "muffler fix" next and the Service Manager from up North stated he had already done this fix and it did not correct the issue. When I told him this did not correct the issue according the SM up North, he started working on the rear end instead...... .......Now you got me wondering what it is as well

I honestly do not know. I will need to look to confirm. The headliner fix will not correct the buffeting issue whatsoever. There is a checklist of items that the GM Engineers require the dealer to go thru to try to solve the issue. The headliner is one of the first things on the list. To me, it was a waste of my time and the dealers money. The next thing on the list is the "muffler" fix.......

Hi Jason- Yes. I fully believe the 'buffeting' was gone with the new ring and pinion "backlash" repair at 42-43 MPH when I drove it home from the dealership (about 3 miles). The 42-43 MPH was the 'sweet' spot for my issue as well, so I was listening closely and drove this speed all the way home. My wife drives the vehicle more than I do and she told me that the buffeting had returned on Tuesday, 4 days after I picked it up. I was out of town during this time and not able to drive the vehicle until this Friday, when I was off for the 4th of July holiday. This is when I noticed it was a true 'vibration' causing the sound, not "just a sound", and this is what my wife was hearing. On a side note: The Service Manager from 1100 miles away called me this morning just to follow up and see how my repair went. Needless to say, this guy has gone way above and beyond for a vehicle his dealership did not sell, and he has never personally met me. Talk about customer service! I only wished he was here in South GA.......he now has a nice gift card in the mail During this call he told me to also be sure, and I quote verbatim, "if the tech found the hour glass wear pattern on the bearings, they should have replaced the axle housing to eliminate this problem coming back." ......Of course I asked this question to my dealership this morning via voice mail and text, still awaiting an answer.....

Thanks for your reply and the info. I will keep it in my back pocket and wait and see if this visit corrects my issue. The buffeting seemed to be fixed until this new issue came about. I did not check the carfax, but I did have them pull a service record on the vehicle on my last visit. My first visit a few weeks ago is all that showed up except for an oil change and when they did the required inspections to call it "certified".

***UPDATE*** Well after a week, my vehicle is back at the dealer. Not for the ‘buffeting’ issue per say, but I have a new issue I believe to be caused by an incorrect installation of the rear end from the repair a week ago. I now have a true vibration resonating from the rear end, to where it can be felt in the steering wheel. The vibration goes in and out, in and out…… ….. ……. count 123,123,123 and it is a constant vibration or “honing”. It can be felt mostly at 53 MPH but I believe is there all the time. I have requested an entire new rear end be installed as I now do not trust them to repair it correctly and I do not know what other damage it may have caused. **other issues** I have a small leak of some type of substance (water like) that is coming from the bottom of the rear view mirror. (see attached pic. white substance is just the camera flash bouncing off of the water on the outside of the window). It has happened before about a month or so ago and I did not think anything about it, but twice now in 3 months and something is definitely not right. Any idea? I have a rattle (screw tapping sound) coming from the driver side area where the door meets the dash. If you wedge your finger between the door and the dash the noise goes away. Any idea what this can be? The passenger side seatbelt housing is so loose, it sounds like it is going to fall off any minute. I have wedge a piece of cardboard to stop the noise for now. Any ideas? I have addressed all the above concerns with my Service Manager. I know I am picky, but I have been patient up until now and I am ready to have this fixed once and for all. For what it’s worth, the rental vehicle I received is a 2015 Tahoe LT. It has none of my issues above, but driving it for about 50 miles, it has plenty of others…….. One last question: I purchased this vehicle as certified used. Lemon laws in Georgia are only good for new vehicles. What are my chances if this cannot be repaired that I will be able to get another vehicle to replace it? Who do I contact? Thanks, cleanfreak

***UPDATE*** I picked up my vehicle yesterday evening after having all of the work in my previous post completed. I am happy to report the buffeting is gone. The reason for the issue seems to be pin pointed down to an incorrect backlash setting in the rear end. Some are set correctly and those with the issue are not. It seems there are 2 types of rear ends that were installed on these vehicles depending on availability at the time of the build. The dealer opened mine up and found the issue. This incorrect setting caused abnormal wear on the ring and pinion as well as the side bearing races. These bearings did have a hourglass wear pattern due to the incorrect setting. They replaced the ring and pinion and making sure the backlash was set per the required specifications and also replaced the side bearing races. I will report back if the buffeting returns, but for now, it is fixed.

***Buffeting Update*** The ring and pinion backlash has been measured and was found to be out of required specifications. The ring and pinion was replaced along with the driveshaft. I went yesterday to drive the vehicle, but it was very hard to make a determination if this indeed solved the issue, as it was raining heavily at the time making it difficult to hear, but I believe I still heard the ‘buffeting’ sound. I also contacted SPDYPRNT’s Service Manager to see if he could help. I have to say, he has gone above and beyond, even though he is over 1000 miles away and not physically dealing with my vehicle. He stated they did the same as my service above, but the ‘buffeting’ sound was not resolved until they replaced the side bearing races in the differential as well. These side bearings had an “hourglass” shape due to backlash being out of required specifications. He also was nice enough to send me the complete parts list and the technician notes on the repair. I have forwarded this information to my Service Manager in hopes he will do the same. I am out of town today, returning tomorrow, and I hope they have time to make this last repair to the side bearing races before I arrive to test drive again. I will update accordingly. Until then, here is the complete parts list and service order the other Service Manager was kind enough to send to me: Parts: QTY 2, 12471686 - SEAL, R/AXL SHF QTY 2, 12479031 – BEARING, RR WHL QTY 1, 14038010 – SHIM KIT, DIFF DRV P/GR BRG QTY 2, 15286384 – RING QTY 2, 22786619 – BEARING ASM – DIFF QTY 2, 22835276 – SHIM KIT – DIFF BRG QTY 1, 22934114 – SPACER, DIFF DRV P/GR BRG QTY 1, 23114036 – GEAR KIT – DIFF RING & PINION QTY 1, 23126912 – DIFFERENTIAL ASM/LSLIP QTY 1, 23168731 – SPACER – DIFF DRV P/GR BRG QTY 1, 23199120 – HOUSING ASM – R/AXL QTY 1, 26063647 – CONNECTOR, R/AXL VENT HOSE QTY 1, 12471607 – MAGNET, R/AXL HSG CHIP COLLECTOR QTY 1, 22943108 – BEARING QTY 1, 22943111 – SEAL QTY 1, 22943106 – BEARING ASM – DIFF DRV P/GR INR QTY 1, 114454 – AXLE ASSEMBLY TECH COMMENTS: Road test numerous times to pinpoint concern. Road test similar vehicle and verified concern is not present. Found concern to be most prevalent on decel at 43 MPH. Install Picoscope and record measurements. When “droaning vibration” occurs, prop shaft 1st order rises to 450nG. Remove rear prop shaft and drive vehicle again. Sensation is still present, but not as severe. Therefore did not swap prop shaft from known good vehicle. Call TAC- case XX-XXXXXXXXXX. Advised (due to Picosope readings) to measure backlash on each tooth of the rear ring gear. Found backlash to be between .011 and .001. Remove differential assembly (it was very difficult to pry from axle housing) and found side bearing races to have an “hourglass” wear pattern. Per TAC, NEC to replace axle housing, ring and pinion, and differential (may be causing ring gear run out concern). Attempted to obtain an assembly, but it is not available. Send out axle for setup due to pinion depth gauge not available in a timely manner. Reassemble rest of axle (axle bearings, ABS reluctors, seals, backing plates, axle shaft, cover). Install axle and road test. (total of 34 miles including diag road test). Sensation is gone.

you got it! I failed to take a pic. Mine was even more boom at the location in white attached.

***A little update*** I took the vehicle this past Saturday to the dealership and rode again with the Service Manager. He was able to hear the buffeting noise (again) and he has contacted the engineer and they have agreed to proceed to troubleshoot the rear end. The first thing they will do is check the ring and pinion for wear and measure the backlash and check for wear on the teeth. They believe the possible issue is a faulty driveshaft not being fully compatible with the rear end, hence causing the issue of the ring and teeth to wear out prematurely. I also had a few minor issues with the second row passenger head rest "rattling" within the seat causing an aweful noise and I have the infamous driver seat movement issue. He ordered all of the parts to repair said issues and they have arrived as of this morning. I will be dropping the vehicle off on Monday to start all of the repairs and I will provide an update to what they find out. During my research of finding the "head rest" noise, I also found the location of the "bass boom" you are referring to. In my vehicle it is actually located on the inside of the tailgate lid across the bottom (below the glass). With the vehicle sitting in the garage and off (no radio, no engine running) and the tailgate closed, I climbed in the back and took my fist and lightly 'banged' around trying to find the noise I was hearing from the headrest and inadvertantly stumbled upon this 'bass' sound. As I banged around on the tailgate lid, I was able to produce a very nice bass boom sound equivalent to two subwoofers. My guess is, when you drive over certain roads, the "bumps" in the road reproduce what I found in this location. It is not an issue that bothers me, but if you find to be a major issue, I suggest looking in the tailgate area.

spdyprnt has replied to my PM with very good info on where he had the repair done and who to contact. I have forwarded the info to my service manager and I have a meeting scheduled with him on Saturday. I believe this to be the fix to the issue. Thank you very much spdyprnt.

Thank you for your reply. You have a PM.

As per my above post, mine is a standard length Yukon or "shortie" with the issue.

I believe each scenario is different depending on the sensitivity of the person experiencing the buffeting. I have come to believe all the vehicles have the issue to some degree. For the record, mine is a SLT, standard length, and I do NOT have the ANC mics. Due to this fact, I believe the mics enhance the issue, which I believe to be a mechanical one. This would make sense if the cotton balls used in those vehicles with mics muffled or canceled the 'enhanced' sound to the degree it could not be heard by that particular individual, or perhaps it did not work on another particular individual because of their sensitivity to the buffeting is greater. The sweet spot for the buffeting in my vehicle is 43 MPH, however, my wife can barely hear the buffeting, where I can hear it loud and clear and feel the pressure. I have been working with my dealer who has been very helpful. The service manager rode with me and we did several test to rule out if the issue was a V4 -vs- V8 mode issue and found out it does not matter what mode the vehicle is in, the buffeting is present. We now have a GMC engineer involved, and he also believes it could be a rear end issue as mentioned by another poster. The next step is to measure the backlash on every tooth in the rear end to determine if the rear end is indeed the culprit. Hopefully I can have this done next week. As for 'just dealing with the issue', we are doing just that. It is not that big a deal to me and as I do not drive this vehicle as my primary vehicle and as stated before, my wife can barely hear the buffeting, so no issue with her. My dealer has been very helpful and determined to figure this out. I understand each situation is different and I'll report back the findings.

I am in the South East (South Ga) as well and I do have the issue. I have the standard length Yukon SLT and just got it back from having the roof TSB done and it has helped with the buffeting, albeit very little. I will say, mine does not seem to be as bad as the others, but it is there......hopefully a real fix will be available soon.