Front brake suddenly grabs on left side only, traction control icon shows briefly

[silverblack1]

It happened yesterday, has never happened before in the 3-4 years I have been riding it. Dealer says it shows no codes, and they can get it to do it by starting a turn. It jerks hard to the left for a fraction of a second, then rides norma.lly. You can get it to repeat in a few seconds by startng a turn. 2008 GS 5 speed.
Bill

 

[billybovine]

The VSS is confused for some reason. Best guess it's a bad sensor. The most likely culprit is the yaw rate sensor in my thinking. Because no code. Also maybe the steering angle sensor if the calibration is way off. But you should have other symtoms.

 

[Easy Rider]

It happened yesterday, has never happened before in the 3-4 years I have been riding it. Dealer says it shows no codes, and they can get it to do it by starting a turn. It jerks hard to the left for a fraction of a second, then rides norma.lly. You can get it to repeat in a few seconds by startng a turn. 2008 GS 5 speed.
Bill

x
So what does that mean exactly ?
That even though they can reproduce the problem, they are at a loss as what to do because there are no codes ??

 

[Chupaca]

Interesting. ...

seems that if this can be done only on a turn that there is a problem with the caliper and feed to that wheel. Possibly pads hagging up and not making full contact or something impeding flow to that caliper. As mentioned above check all sensors involved in the stability control system...VSS ABS etc otherwise check the caliper pads and brake lines...

 

[billybovine]

seems that if this can be done only on a turn that there is a problem with the caliper and feed to that wheel. Possibly pads hagging up and not making full contact or something impeding flow to that caliper. As mentioned above check all sensors involved in the stability control system...VSS ABS etc otherwise check the caliper pads and brake lines...

How could a defective caliper cause the VSS light to come on at the same time?

 

[oldguyinTX]

Has the brake fluid ever been flushed and changed? On a 2008 it should have been changed four times by now. If not, really dirty brake fluid could be your problem.

 

[Easy Rider]

How could a defective caliper cause the VSS light to come on at the same time?

Sensor indicates that something is slowing ONE WHEEL, when the computer knows that no braking pressure is being applied.
Binding caliper, bad wheel sensor or a hose being pinched in a manner that it puts pressure on the caliper.

 

[billybovine]

Sensor indicates that something is slowing ONE WHEEL, when the computer knows that no braking pressure is being applied.
Binding caliper, bad wheel sensor or a hose being pinched in a manner that it puts pressure on the caliper.

If the light came on because of a problem there would be a code. No code. The VSS light comes on because it thinks there is a reason to step in and is applying the front left brake.

 

[Snowbelt Spyder]

Yeah. Looks like you're getting an unnecessary / premature activation of the VSS system. The light coming on momentarily is a key, as Billy mentioned. For our later year models, there is a quick and simple Yaw Rate Sensor Reset procedure done through BUDS. You might ask your dealer if that also applies to model year 2008. He may have to look through the manual or fire up the program to see if there is a page for that. If so, I would recommend on doing that first since it only would be a 5 minute job. Checking the brakes - always a good idea anyway.

 

[Easy Rider]

If the light came on because of a problem there would be a code. No code. The VSS light comes on because it thinks there is a reason to step in and is applying the front left brake.

.
Yes that is possible too.
But is still is an assumption that may not be true.

If it IS true, the culprit might be the sensor on the front RIGHT wheel, erroneously reporting that the right wheel is slipping.

 

[silverblack1]

It was just in for a "Brake Failure " warning light, and they changed the brake fluid and adjusted the E brake cable, and lubed the E brake cable. I will call the service dept. with your suggestions. Thank you to all that made suggestions-they all sound good.
Bill

 

[silverblack1]

The latest: Service department has been in touch with BRP, and have received suggestions as what to look for-this is a unique problem-no answers yet. Is a used one a possibility?
Bill

 

[silverblack1]

Got the call from the service department-the problem has been diagnosed as a bad VSM-vehicle stability module, with a fix it price including labor of $2800.

 

[billybovine]

Sorry that the most expensive part in the system failed. I thought it would throw a code if it was starting to fail. That's why I went with a bad sensor.

 

[silverblack1]

OK, all fixed-original quote for repair was $2,800 because it needed a new VCM. As it turned out, BRP suggested wiping the memory on the VCM, and re-initializing it. Worked fine, no new parts, just programing. Total cost to fix-$650.

 

[billybovine]

OK, all fixed-original quote for repair was $2,800 because it needed a new VCM. As it turned out, BRP suggested wiping the memory on the VCM, and re-initializing it. Worked fine, no new parts, just programing. Total cost to fix-$650.

Thanks for this post. I did not know the VCM could be cleared and reflashed. Good to know if someone else has a similar problem.