2015 GMC Yukon - Rough Highway ride - Possible Magnetic Shock Failure?

page1 · September 10, 2020

Here is what I got out of my reader /writer:

3. Body control module---(12), which means 12 errors with a ‘Fault’ status, within my module (s)

Here are the additional details I got:

3.1 B1325-03
Control module power circuit - Low voltage
DTC history status : History Since DTC clear : Passed and failed Last test : Passed This ignition cycle : Passed MIL status :

With regards to voltage in each shock, the looked normal both before and after the clear

dwchapmanjr · September 10, 2020

@page1 - Thanks! I saw similar although I had no codes, my ride height voltages seemed normal and fairly symmetrical. My command current (mA) seemed normal for what I would suspect. I drove around for a while but didn't see much stick out while reproducing it although 1 strut or the other would randomly jump up to 1900-2000 mA. The rears seem to stay around the 200's for most of the driving and but the fronts jump all over the place likely taking the brunt of the shocks.

dwchapmanjr · September 12, 2020

I'm wondering if anyone has had luck going to the dealer and getting a new calibration. There seems to be one specific to address this and mine likely doesn't have it since I've never had a ESCM calibration loaded.

Second one from bottom. Note the most recent one is the top so there have been quite a few revisions. Took a bit of research to find out these are not sequential. Going to ask the dealer to try to load this and possibly a road force balance and diagnostic.

Thought I'd share

https://tis2web.service.gm.com

dwchapmanjr · September 14, 2020

I took it in and they did not seem to find anything so I took it in with the calibration sheet but I'm not sure they did anything with it. I asked the service advisor about the calibrations and either the vehicle didn't need it or they didn't check so I may check with another local shop to see if they can check the calibration.

They did a road force balance upon my request and it seems a bit better but the alignment is off. Could be from doing the front shock. It was noticeably worse after the rotation and balance though which may point to an issue. I'll go in for an alignment this week or next and see if they can check the calibration ID on the suspension module since I'm not confident the dealer did.

dwchapmanjr · September 16, 2020

I brought mine to the dealer Monday. They couldn't find anything wrong and recommended a road force balance. Interesting thing when I pulled out of the dealership and got onto the highway. Hard pull to the left. I didn't have time to turn around. Figured it was an alignment issue.

Brought it to a local shop to check alignment and any ESCM calibrations. They said alignment was perfect and calibration was on the latest. Dealer must have updated the calibration when doing the other shock.

They road forced it again and rotated and the pull went away. I'm fairly sure I have what's called Tire Conicity. The pull started immediately after the first rotation of these new tires.

I'll be calling the dealer to see if I can get that tire replaced under warranty. Thought I'd share since I never heard of conicity before.

https://artsautomotive.com/home/art-icles/shop-articles/hunter-gsp9700-road-force-balancer/

dwchapmanjr · September 21, 2020

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)"

Quote

There have been some reports of Z95 MR system ride improvement following shock replacement and reprogramming the suspension control module; later to have the ride feel return to the original level of customer concern. This phenomenon occurs during a period of learning for the suspension control module of the shock characteristics. Once the learning period is complete, the module will lock in the shock characteristics for that specific vehicle.

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.

Edited September 21, 2020 by dwchapmanjr
Updated TSB

dwchapmanjr · September 30, 2020

Looks like its been about 10 days since I updated. I've been trying to narrow down the vibration. In my search I came across the term NVH or Noise, Vibration, Harshness. GM dealers are supposed to have a PicoScope with NVH module. My service advisor indicated to me that they can do that so when I'm ready to come in, they will. With that said, I wanted to understand it better and documented it in an article I wrote below. Sharing incase it helps anyone else with similar issues.

I had an interesting discovery these past few days. In Houston, we've had a bit of a cold spell so my morning drives were a little better. I've noticed my vibration seems to get worse as the vehicle warms up and I drive it for a while. In the morning or cold drives, its almost back to normal. Today I was driving and noticed it started as soon as one tire warmed up to 38psi so I pulled over and deflated it to 36 and it was better for 10 mins. Then the other front tire got to 38 and same thing so I deflated it too and it was better for about 10 mins.

I'm not sure if the smoother ride by slightly deflated tires is compensating for something else or if a tire issue is the issue. One of the front tires is brand new though as it had a bad tire pull (tire conicity). Presumably the other front was in the pair with it before being replaced.

In any case - if you have too much time on your hands or want to be better equipped to speak to the dealer about vibrations, below will arm you with some tools. I still need to narrow my process down as my numbers are a bit all over the place. I think I have yet to find a great place I can mount my phone to capture the vibrations that is uniform.

https://blog.woohoosvcs.com/2020/09/quick-and-dirty-noise-vibration-harshness-quantification/

dwchapmanjr · October 5, 2020

Likely my last post. Dealer took it for a drive on a known smooth surface and they could still slightly detect it but said they've just had complaints bout this particular tire type/tread(Bridgestone Dueler H/L Alenza). Said I should likely replace with some Michelin tires the next round. That the tires on there are perfectly balanced but this type of tire has this complaint. Unless I want to cough up $900 or so for a new set, it'll probably be a few years unless this gets worse. Dealer has been reputable and knowledgeable so I believe them and for my sanity (if there's any left), it has gotten good enough to live with (for now).

Interestingly with the cold weather and transmission work I had done its better. We'll see how that holds up.

chamilun · June 8, 2024

SuOn 8/29/2020 at 10:31 PM, jmac said:

I just replaced all four shocks on my wife's 2016 Yukon Denali XL and it is still riding like crap. The back shocks were toast and one of the front shocks had fluid leaking out. Yes ride did improve but not to what I expected. My Jeep rides better than my Denali and that just is not right.

Joined just to post this. The above post is 100% correct. Sort of.

The autel ap200 and newer can fix these new shock issues. But it's not clearing codes.

It has a procedure to reset the ride height sensors. Has you park on level ground then does the procedure.

Fixes the harshness.

I noticed mine on new front and back was still bouncing like it wasn't dampening at the right time. This takes care of it. What you do is manually selection the suspension category then manually test them

chamilun · June 8, 2024

Also. There are a million post about it being tires. It's not. We have Michelin and it drove like crap. Also fronts must be 4wd not just magneride. There's a difference per strut masters. Assuming you have 4wd

GovtMule66 · June 12, 2025

On 6/8/2024 at 1:50 PM, chamilun said:

Joined just to post this. The above post is 100% correct. Sort of.

The autel ap200 and newer can fix these new shock issues. But it's not clearing codes.

It has a procedure to reset the ride height sensors. Has you park on level ground then does the procedure.

Fixes the harshness.

I noticed mine on new front and back was still bouncing like it wasn't dampening at the right time. This takes care of it. What you do is manually selection the suspension category then manually test them

Was you able to reset/relearn the right height sensors on your vehicle using the Autel AP200? I have a 2015 GMC Sierra 1500 Denali which has the Z95 magneride suspension package on it. Unfortunately the front shocks on my truck have become so stiff you can't even press the front end down standing on a ladder. I would like to rule out all possibilities before I sink $1200 in new front shocks/struts. I've called a few dealers in my area but they act like there is no test that can be run to see if any faults exist on a suspension package. Unless I am reading several online sites wrong that is not correct which is aggravating to say the least.

Edited June 12, 2025 by GovtMule66
spelling

newdude · June 14, 2025

On 6/12/2025 at 1:11 PM, GovtMule66 said:

Was you able to reset/relearn the right height sensors on your vehicle using the Autel AP200? I have a 2015 GMC Sierra 1500 Denali which has the Z95 magneride suspension package on it. Unfortunately the front shocks on my truck have become so stiff you can't even press the front end down standing on a ladder. I would like to rule out all possibilities before I sink $1200 in new front shocks/struts. I've called a few dealers in my area but they act like there is no test that can be run to see if any faults exist on a suspension package. Unless I am reading several online sites wrong that is not correct which is aggravating to say the least.

Put shocks in it.

GovtMule66 · June 14, 2025

6 hours ago, newdude said:

Put shocks in it.

And if the problem persist then what?

newdude · June 15, 2025

4 hours ago, GovtMule66 said:

And if the problem persist then what?

It won't. If they are collapsed, they are bad. You can jack up either side of the front end, if the wheel doesn't droop down as you raise the truck, the shock(s) are F'd and need to be replaced.

9 times out of 10 on these Magneride its the shocks that failed. Replace them with new ones or get rid of the Magneride and put the regular shocks in and bypass resistors.