jfischer

Hi, I'm new to the forum and excited to see all of the info out here! I have an 09 Suburban Z71 with 126k miles on it that has been frustrating me since I purchased it this past spring. I purchased it with a 2" lift/leveling kit on it and slightly oversized tires (275 70 R18) which is why I fell for this truck. Unfortunately, when I test drove and bought it, it was about 4 degrees outside and icy roads so I didn't a true feel for what it has to offer. Well... Fast forward a bit. I've been dealing with steering drift and the Stabilitrak system misfiring. I think we have the steering issue mostly fixed (new ball joints, steering rack, intermediate steering shaft, power steering pump, stabilizer links, alignment). We are now just trying to figure out the last little bit of "slop" in the steering wheel. It seems like the splines aren't quite as tight fitting as I'd like but that's not the reason for the post.

What I'm most frustrated with is the Stabilitrak system. I've read pages of posts from other members talking about their system needing service with the light constantly on. I don't have that problem. My issue is that when going around turns, my Stabilitrak system turns on activating the brakes and flashes the light thinking that the truck is going into a slide. When you straighten out the wheel, everything goes back to normal. It doesn't happen on all turns. Just about 60-70% of them. Just like my steering issue, we've thrown a ton of parts at this. Wheel speed sensors, electronic brake control module, YAW sensor as well as checking all wiring from wheels to the computer including the plugs around the shock towers. Oh yeah, also checked the steering angle sensor...

After all of this, the GM dealer said that this is happening due to the oversize tires. They are approximately 5% larger than factory size (265 65 R18). We've calibrated the speedometer to be accurate but was told that the ECM cannot be re-calibrated and I'd need to buy the right size tire to get this to go away. Does this sound right? I've seen way too many late model trucks on the road that have been lifted running larger tires and have a hard time believing that all of them are dealing with this issue.

As maybe you can tell, I'm giving this truck a good shot without wanting to pull off the mods but I'm running out of patience. Any help or suggestions are welcome!

Thanks in advance!

cleveland63b

codes? wheel bearings tight? OEM parts? How did you check the wiring? lots of variables here.

jfischer

Hey Cleveland63B,
No codes. The system simply thinks the truck is in a skid and activates the Stabilitrak system when turning. All parts that have gone onto the truck are OEM and not Napa, Etc. The left front wheel hub assembly was replaced. The right is tight and that is the only wheel speed sensor that is original. The speed sensors were all traced from the sensor to the control box by opening up the harness as well as was tested with a jumper wire directly from each wheel directly into a scanning tool one by one while driving. All checks out ok.

cleveland63b

honestly my next step would be to see if maybe you have a friend that has stock size wheels and tires and swap them out to see if that changes anything

bullcreekoffroad

Will the scanner tell which wheel it thinks is skiding? I've bought new hub assemblies with faulty sensors. i don't believe tire size is the problem.

cleveland63b

if theres no codes its a guessing game unless you have a scanner that can graph the speed sensors but 99% of the time if a speed sensor is dropping signal there will be a code stored.

tech2

the dealer can set the new tire size in the ebcm with the factory scan tool. This will allow the speedo to run correctly without any aftermarket calibration.
I know this as I have done this with mine.


I was wondering if they are any steering wheel sensor dtc or if the steering wheel centering needs to be done after the alignment? this procedure is required after alignment for some stability systems and some electric power steering systems.