Service Stability System

[FINN444]

Thursday I was backing down my driveway to go to work, and Service Stability System popped up on the DIC, when I left work it was gone, and didn't say that anymore. Now today I was backing down my driveway and this popped up on the DIC again. The weird thing is that I was in about the same location, on the driveway, as the first time this happened. It was on a slight downhill turn... I drove to a store and when I went out and started my car, the message was gone... No other dash lights came on, that are common for when a WSS goes bad, so I'm kinda stumped on this?? I did just put my new GXP wheels on, so I'm not sure if that did something, but I also have 16" winter rims/tires that I have had on my car, but this never happened when I had those on... I know that you can use a Tech2 to scan this, but will it say anything if there is no error message on the DIC? Anyone have any ideas what this could be?
Thanks,
John

[redzmonte]

could be one of a couple things.. Did your stability system try and activate when it faults? My yaw sensor went bad and it actually activated the stability system when turning right and going over a slight dip. new Yaw sensor and no problems for me. Steering angle sensor and wheel speed sensors are what i see more common on GM car going bad.
* Bad Steering angle sensor
* Bad wheel speed sensor (fronts are part of hub, rear i think are external)
* Bad Yaw sensor
* Bad ground
* Low battery charge

Best thing to do is start with a ABS Code scan and see if it gives you a code.. then have it scanned to monitor WSS, Steering angle and yaw rate. It should show a fault code reporting as "History Code" if it is not showing a fault on the dash it may not show a current Code.

[FINN444]

It didn't activate the stability system. As far as I could tell there was absolutely nothing different about my car except the warning on the DIC...

[ddalder]

As suggested, have it scanned and see what comes up. If you don't wait too long, there should be a history code if the fault isn't active at the time it's checked. Yaw rate and accelerometer sensor failures are pretty rare (I actually don't recall hearing anyone on this forum needing to replace one) but wheel speed sensor and steering wheel position sensor failures are not. The yaw rate sensor is located in the trunk near the remote control door lock receiver and the accelerometer is under the back seat near the fuse block. If the problem is the steering wheel position sensor (my stab in the dark guess) then the intermediate steering shaft needs to be disconnected to replace it. I believe there's a write-up somewhere about that. Personally, I just removed the whole column when I did mine.

Activation of StabiliTrak is not necessary to generate an error message. The system monitors the sensors all the time.

[FINN444]

Ok, sounds good, I'm really hoping it is either the accelerometer or yaw sensor, because I'm not a very big fan of working around the steering column... wheel bearings don't really bother me, their pretty easy to do once you have a method that breaks them loose from the steering knuckle. I have an uncle who used to be a mechanic so if worse comes to worse I'll see if he would help with the steering wheel sensor.

[FINN444]

Ok, sounds good, I'm really hoping it is either the accelerometer or yaw sensor, because I'm not a very big fan of working around the steering column... wheel bearings don't really bother me, their pretty easy to do once you have a method that breaks them loose from the steering knuckle. I have an uncle who used to be a mechanic so if worse comes to worse I'll see if he would help with the steering wheel sensor.

[ddalder]

The code(s) will really help. If you're looking for a steering wheel position sensor I'd recommend buying new. They are a fairly common failure but a bit of a pain to replace. The yaw rate and accelerometer sensors are much easier to replace and Andrew would have replacements. Like I said, not a common item to fail so I wouldn't hold your breath that either of these is the problem. It could also be a fault with the ABS module because that's the module that manages stability control.

[ddalder]

The steering wheel position sensor is a contact type sensor which means every time you turn the wheel there is a contact moving against another. Optical would have made it bullet proof but more expensive. Because of its design, it's really not a question of whether it will need replacement but when.

[CMNTMXR57]

A search on "Service Stability System" here on this board would give you all the answers;

There are three pieces used in the stability system that require replacement when the stability system becomes inoperative and you've troubleshot it correctly. I have listed those above. In addition, the electronic brake control module (EBCM) can be a culprit too.

1) First you perform an ABS system check. If there is a fault in the ABS system, this is where the WSS comes into play. But NOT anything to do with the VSES!

2) you check that the VSES (Vehicle Stability Enhancement System) centers for roughly 30 seconds. If it doesn't, go to step 3, otherwise check all connections and wiring harnesses for intermittent connections.

3) Using your T2 (or equivalent), perform a steering wheel position sensor test. If the SWPS checks out, move on to the next step. If it doesn't, replace the SWPS.

4) Using your T2 (or equivalent), check the lateral accelerometer input voltage in the VSES. It should return about 2.5v. If it does, then the next step will be to test the yaw rate sensor. Otherwise, if it doesn't, replace the lateral accelerometer.

5) Using your T2 (or equivalent), check the yaw rate sensor. It too should return 2.5v. If it does, move on to the EBCM. If your yaw rate sensor doesn't return 2.5v, replace the yaw rate sensor.

6) Replace the EBCM. If it isn't programmed/setup properly, that could be the problem, and you'll be generating a C1248 or C1255M3 code and possible incorrect operation of the system.

From this thread;
viewtopic.php?f=17&t=14974&p=203215&hil ... em#p203215

[FINN444]

Ok I'll try to get it scanned to see which it is