TC Shudder, misdiagnosed as 4WD issue by myself

[phatz_hatz]

Around 40-50 MPH with Auto 4WD selected, feels like front passenger side tire is either locking up or “ sputtering “ When i put into 2H it seems to alleviate issue a lil bit but still happens intermittently. Is this an issue with auto braking assist or something to do with the 4WD module. Almost feels like hitting rumble strips on a highway. Have 100k warranty 2016 LTZ Tahoe with 80K, just want insight if anyone’s ran into this issue before. Newer vehicle to me, not used to all this electronically controlled shit. Thank you in advance.

 

[swathdiver]

Around 40-50 MPH with Auto 4WD selected, feels like front passenger side tire is either locking up or “ sputtering “ When i put into 2H it seems to alleviate issue a lil bit but still happens intermittently. Is this an issue with auto braking assist or something to do with the 4WD module. Almost feels like hitting rumble strips on a highway. Have 100k warranty 2016 LTZ Tahoe with 80K, just want insight if anyone’s ran into this issue before. Newer vehicle to me, not used to all this electronically controlled shit. Thank you in advance.

Does it do it also in 4HI? If not, this seems more like a transfer case issue. If so, it's likely a front differential issue and should be taken in, drive in 2HI until it's fixed.

Do you drive in 4AUTO all the time?

 

[Fless]

Have the wheel speed sensors been graphed and compared to see if that one is off a bit?

Brake caliper "floating" okay? Slide pins lubed and free?

 

[phatz_hatz]

Does it do it also in 4HI? If not, this seems more like a transfer case issue. If so, it's likely a front differential issue and should be taken in, drive in 2HI until it's fixed.

Do you drive in 4AUTO all the time?

Just got the truck 2 weeks ago, when i test drove it, it was in auto 4. When we picked it up they put it in 2H. So curiosity yesterday put it in auto 4 and it started happening. Put it back in 2 Hi haven’t tested it in 4HI.

 

[swathdiver]

Just got the truck 2 weeks ago, when i test drove it, it was in auto 4. When we picked it up they put it in 2H. So curiosity yesterday put it in auto 4 and it started happening. Put it back in 2 Hi haven’t tested it in 4HI.

Ok, test it out in those positions and let us know.

Running around in 4Auto wears out the components prematurely. It was not made for daily use over the life of the vehicle. Folks who drive in 4Auto all the time are lucky to get 100K miles on their transfer case before requiring overhaul.

 

[phatz_hatz]

Ok, test it out in those positions and let us know.

Running around in 4Auto wears out the components prematurely. It was not made for daily use over the life of the vehicle. Folks who drive in 4Auto all the time are lucky to get 100K miles on their transfer case before requiring overhaul.

update, issue still occurs even when in 2H. have not tested 4HI. As i believe it is not a 4WD issue as i initially suspected, i'm leaning towards may have to do something with the brake assist or vaccum pump associated with the braking system. very intermittent issue. I am afraid if i bring to the dealer and they drive it, it will not do it and i will be stuck with the issue. i know the pump was replaced at about 60k miles. just very odd to me why it would be doing that without the brake pedal even being applied. If this post has to moved to a different section considering it is not pretaining to the engine and drivetrain. Thank you in advance for any insight !

 

[Fless]

Seems to be isolated to one wheel, so I'm not sure I'd suspect the vacuum pump yet. Get a good scanner on it and watch the wheel speed sensors to see if they are all reporting the same (with particular scrutiny on that RF one). Check that caliper for proper operation and abnormal pad wear, maybe a rubber brake hose collapsing or the like.

 

[phatz_hatz]

Seems to be isolated to one wheel, so I'm not sure I'd suspect the vacuum pump yet. Get a good scanner on it and watch the wheel speed sensors to see if they are all reporting the same (with particular scrutiny on that RF one). Check that caliper for proper operation and abnormal pad wear, maybe a rubber brake hose collapsing or the like.

Its honestly both sides at this point, sometimes both at the same time. im gonna call dealer i have a 100k warranty on it and i just got the truck a little over 3 weeks ago so they cant try and say i missed a maintenance schedule. Regardless there is an issue, id attempt to tackle it myself but all this technology is a little out of my league. Got the warranty for a reason might as well use it while i have it. thank you for your advice, i am looking into getting and MDI scanner at some point in the future.

 

[Fless]

After it's fixed, please share what they did to it. Inquiring minds want to know...

 

[phatz_hatz]

After it's fixed, please share what they did to it. Inquiring minds want to know...

Update on this, as i do not drive the vehicle as often. It is for the wife as she described it to me. now that i have driven it over the past couple of days, i have came to the final conclusion that it is something with the transmission, vibrations and or shudder happens more towards middle/backend of the truck. it is a shuddering/hesitation in gear shifts at highway speeds, sometimes at slower speeds. From all the reading and research i have found. I believe now it is likely the Torque converter shudder i've read so much about. I am bringing it to the dealer on Feb 12th. I almost want to try and do a full flush and filter, and install that updated thermal bypass valve to moderate trans temp. Ive noticed it also becomes more noticable when the trans heats up to operating temp, at least what i believe to be operating temp as the LTZ does'nt seem to have an info display on trans temp. Will keep y'all updated after the dealer. Have a feeling dealer is gonna try and stroke me. Just hope if it is close to catastrophic failure they will uphold the extended 100k "bumper to bumper" warranty they sold to me upon purchase of the vehicle last month.

 

[NickTransmissions]

Update on this, as i do not drive the vehicle as often. It is for the wife as she described it to me. now that i have driven it over the past couple of days, i have came to the final conclusion that it is something with the transmission, vibrations and or shudder happens more towards middle/backend of the truck. it is a shuddering/hesitation in gear shifts at highway speeds, sometimes at slower speeds. From all the reading and research i have found. I believe now it is likely the Torque converter shudder i've read so much about. I am bringing it to the dealer on Feb 12th. I almost want to try and do a full flush and filter, and install that updated thermal bypass valve to moderate trans temp. Ive noticed it also becomes more noticable when the trans heats up to operating temp, at least what i believe to be operating temp as the LTZ does'nt seem to have an info display on trans temp. Will keep y'all updated after the dealer. Have a feeling dealer is gonna try and stroke me. Just hope if it is close to catastrophic failure they will uphold the extended 100k "bumper to bumper" warranty they sold to me upon purchase of the vehicle last month.

The converter is shot; you can confirm yourself by plugging in a bidirectional scan tool, taking the Tahoe for a drive with TCC slip speed and duty cycle displayed. If TCC slip speed is in excess of 10-15 rpm or so when duty cycle is like 70-80% or so (and you feel the shudder) that's converter going south.

 

[phatz_hatz]

The converter is shot; you can confirm yourself by plugging in a bidirectional scan tool, taking the Tahoe for a drive with TCC slip speed and duty cycle displayed. If TCC slip speed is in excess of 10-15 rpm or so when duty cycle is like 70-80% or so (and you feel the shudder) that's converter going south.

I was waiting for you to come into this thread lol... Now my next question is should she continue to drive it until our appointment at the dealer or should she refrain from use for the meantime to try and prevent any further damage. We are expecting our first child in march and need the truck to be well a truck i intended to get for safety and reliability. OR should we just drive into the ground per say to get the dealership to do the overhaul or replace with a reman. first dealer bought vehicle with a warranty, unsure of how these dealer warranties work.

 

[NickTransmissions]

I was waiting for you to come into this thread lol... Now my next question is should she continue to drive it until our appointment at the dealer or should she refrain from use for the meantime to try and prevent any further damage. We are expecting our first child in march and need the truck to be well a truck i intended to get for safety and reliability. OR should we just drive into the ground per say to get the dealership to do the overhaul or replace with a reman. first dealer bought vehicle with a warranty, unsure of how these dealer warranties work.

While this isnt common by any stretch, if the TC completely grenades itself, it can take the pump out and strand you or whomever is driving the vehicle. Id park it and use another vehicle in the meantime, just to be on the safe side. Let the dealer swap it out (trans and converter).

 

[phatz_hatz]

While this isnt common by any stretch, if the TC completely grenades itself, it can take the pump out and strand you or whomever is driving the vehicle. Id park it and use another vehicle in the meantime, just to be on the safe side. Let the dealer swap it out (trans and converter).

Thank you for your input sir, very much appreciated. Will continue to update here after the dealer visit.

 

[Brian1133]

Did you ever find out the issue? I have shuddering only in 4auto.

 

[Bigburb3500]

Did you ever find out the issue? I have shuddering only in 4auto.

It was the torque converter. Nothing to do with the with the 4wd system…

 

[Brian1133]

Ok, thanks. It was snowing yesterday and I put my truck in 4auto and it was more like a constant rumbling at city and highway speeds. Put on 2wd and it went away.

 

[Geotrash]

Ok, thanks. It was snowing yesterday and I put my truck in 4auto and it was more like a constant rumbling at city and highway speeds. Put on 2wd and it went away.

I had a front differential growl in my '02 Suburban (same basic front differential design) that would show up in 4WD or 4WD auto only. Turned out to be a failed bearing. Took it to a driveline shop and they repaired it for $1200. Either way, take it to a shop who can either put it on a lift to troubleshoot, or can run it with a set of chassis ears to find the source.