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Service stability system and service abs

15K views 11 replies 7 participants last post by  Rboughne1 
#1 ·
So I was driving along today and the service stability system and service abs messages flashed across the DIC, with the abs and traction control disabled lights on. I pull over and throw on my obd2 reader and no codes are set.

I spot checked the fuses and they look good. Any ideas on other things to check?

My apologies for not searching this first, it's hard to find stuff from the forums mobile app.

Thanks,

Steve
 
#7 ·
Posted numerous times before. This is a general explanation and troubleshooting where both the stability system AND ABS errors are generated. It is not STS-V specific but it is from GM, although I can get the specific STS-V list.

There are three pieces used in the stability system that require replacement when the stability system becomes inoperative and you've troubleshot it correctly. Where the two systems cross (ABS and Stability Control) is in step #1 and step #6, those being WSS and the electronic brake control module (EBCM).

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.

No where in ANY of this, other than making sure the ABS system is funtioning correctly, is mention of the wheel speed sensor (WSS), wheel hub, etc. Why you ask?? The WSS is ONLY used for computational needs of the ABS/traction control system. NOT the Vehicle Stability Enhancement System (VSES).

I just went and looked in my Techline manual for 2004. This is EXACTLY, verbatim, from GENERAL MOTORS;
The vehicle stability enhancement system (VSES) includes an additional level of vehicle control to the EBCM. The VSES is activated by the EBCM calculating the desired yaw rate and comparing it to the actual yaw rate input. The desired yaw rate is calculated from measured steering wheel position, vehicle speed, and lateral acceleration. The difference between the desired yaw rate and actual yaw rate is the yaw rate error, which is a measurement of oversteer or understeer. If the yaw rate error becomes too large, the EBCM will attempt to correct the vehicle's yaw motion by applying differential braking to the left or right front wheel.

The VSES activations generally occur during aggressive driving, in the turns or bumpy roads without much use of the accelerator pedal. When braking during VSES activation, the brake pedal will feel different than the ABS pedal pulsation. The brake pedal pulsates at a higher frequency during VSES activation.

Steering Wheel Position = Steering Wheel Position Sensor (SWPS) located in your steering column
Vehicle Speed = Vehicle Speed Sensor (VSS) located on your transmission. This is NOT to be confused with your WSS out at the axles.
Lateral Acceleration = Lateral Accelerometer sensor
Yaw Rate = Yaw Rate Sensor
 
#10 · (Edited)
Going to be bearings. If you replaced them in November, and they're already bad, you either got stuck with the cheapo $100 ones, or a defective and/or improperly installed (i.e., over-torqued) SKF, Timken, or AC-Delco. FYI - SKF manufactured the factory bearings for this car, hence the Delco rebranding. Check your receipt to see which ones your shop banged you for. If you paid for Timken or Delco/SKF, and that's what's stamped on the part, they'll still be under warranty for replacement within a year, I believe. If you paid for Timken or Delco/SKF, and that's NOT stamped on the part, well, you have a fraud claim in the works, and hence bigger problems. You'll need either Timken or Delco/SKF X-Tracks to get good life out of the bearings on this car (and by good, I mean a dismal 40k miles - this car EATS bearings). My rears were $210 each SHIPPED off Rock Auto when I did them in October, and I checked EVERYWHERE. I ended up with the factory AC-Delco replacements made by SKF off their site, as they were the cheapest at the time.

My mechanic friend checked NAPA for stock replacements, and the only option in stock was Timken at the time. Amazingly, they wanted almost $450 EACH for them, HIS COST, for which the suggested retail charge to the customer was $550 EACH. I said "F"-that, and started hunting online. Rock Auto turned out to be half price for the same thing. Made me a Rock Auto shopper. Not for everything, mind you, but certainly for these replacement bearings. It was the first time I'd ever seen "wholesale" (i.e. mechanic) NAPA parts not be cheaper than just about everywhere else. Just shop around, you may find a better site than Rock Auto for these, because pricing is ALL OVER the place, but only shop Timken or Delco/SKF.

Here's the link to Rock Auto bearings for the "V". Scroll to the bottom, as the cheapo 6-stud ones are mixed in at the top, along with the 5 stud versions for the regular STS. You'll need the six-lug versions that fit the J56 brake package; GM Front part #15816313 & GM Rear part #15819433. Your choices are AC-Delco (rebranded SKF, as stated before), SKF, or Timken. Notice the price variation between the brands...If it's a front you're only banged $164 for the SKF, and AC Delco rears are only $198. Mix and match between them for the cheapest pricing if doing all four. Looks like prices are down about $20, too. Good timing for you, as compared to me!

http://www.rockauto.com/catalog/raf...g+%26%2338%3B+Hub+Assembly&blanktemplate=true
 
#12 ·
Behind you is rear, in front of you is nose. That's the best I've ever been able to do when they first start humming. Usually I'll run it until the bad corner is obvious by sound or feel (sound= vehicle jacked up and stethoscope on knuckle when wheel is spun/feel= Slight play in the wheel either up/down or left/right when jacked up). They'll go 2000 miles after the light comes on. Just run 'em until you can identify it. Just don't run em 10k miles.
 
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