I posted ages ago about problems with VSC lights coming on which the dealer diagnosed as a faulty speed sensor. I had the left, then the right replaced, and another one recently I think (I'm losing track, and patience). Each time, the lights came on a few months after the install. The last install was 2 months ago I think.

Well, coming home tonight from the hardware store, I go over a bump in the road (uneven asphalt joint, nothing major) and sure enough, the lights are on again. Typically I'll start driving the next time I start the car and the lights will go out (the computer figures it was just a bad reading from the speed sensor apparently), then if it goes like the previous times, the car will become more and more sensitive to bumps, with the lights coming on more and more often.

The dealer has said they don't blame my rims (or the suspension mods they installed) and that the car shouldn't have this problem. My service manager also said last time if it happens again they're going to get some corporate technician in to look at it. So at least the dealer is being good about it.

But it just sucks that this keeps happening. Strangely, it didn't happen when I drove the car pretty hard with DaveGS4 and Dexter up in the NC mountains around Asheville. Only on the occasional lousy bit of Atlanta road!

I'm getting sick of this...

 

my lights came up last week also...mine came up as i was coming to a stop at a stop light right after exiting the freeway...as i pressed the accelerater after the light turned green, my car wouldn't really move...it felt like i ran out of gas...it'll jerk and stop like a bad "stick" driver. I turned off the engine and restarted it and the problem went away (but not the lights)....
It's been a week and the lights simply went away

not sure what to do now..i try to avoid the dealers around the bay area and wait till i go back to longo lexus in LA to get stuff checked out...

 

amlin - from what I've read on here, I think your problem is a throttle position sensor. Even if the lights went out, I'd go to your dealer if it's under warranty because they can see why the lights went on through their computer.

 

it is the throttle position sensor this means its starting to wear out, my sensor is already worn out and my light pops up constantly its a pain in my ***

 

I believe the two primary inputs to the VSC are the yaw sensor (lateral accelerometer) and the steering wheel rotational position sensor. If the steering wheel is centered and the yaw sensor "says" the vehicle isn't moving in a straight line then the VSC will try to "straighten" the line of travel, right rear coming around (oversteer) it will apply the right front brake. If the steering wheel is off-center to the right and the vehicle is still traveling in a straight line the VSC will apply the appropreate brake to help correct the vehicle's line of travel.

I think, not sure of this, if the yaw is "out of wack", the incorrect line of travel persists then the VSC will de-throttle the engine just as it will with Trac if wheelspin persists.

It truly sounds as if your YAW sensor is not secured to the body of the vehicle and might be bouncing around and generating accelerometer outputs due to its movement independent of the vehicle itself. Or a loose or intermittent connection at the steering wheel position sensor or the yaw sensor would produce the symtoms you both describe.

 

wwest - hi - haven't seen you here before, only Edmunds - welcome. That's an interesting explanation, thanks. The dealer keeps telling me though that it's the wheel speed sensors that show up with error codes on their computer. I will be sure to mention your thoughts when I go in again.

Thanks. This is really getting old. So old, I'm beginning to think about getting a different car (not sure what, but not a Lexus, at this point).

 

Sorta knowing and understanding how VSC works, or is supposed to work, I don't quite see how a wheel speed sensor could activate any of the VSC modes. Have you checked to see that all of the tires have reasonably equal inflation. The olds Alero will report a flat tire if all of the wheel speed sensors but one indicate the same rotation speed. Clever, aren't they?

I wonder if you are somehow getting a wheel sensor "fault" and the service manager is missinterpulating it to relate to your VSC problem. But I'll go up and re-read the GS VSC diagnostic section in the GS shop manual to be sure.

 

Bitkahuna I had the same problem and I had to bring the car back to the dealership three times. I have the same set up as you L-Tune and Sways. The sensor that keeps going out over bumps was my right front.

Solution: The front say bars are on incorrectly your dealer need to reverse it. It is difficult to detect. I have driven my car to NYC (bumps) and the car sensor light did not go out. I am very happy now knowing that winter is here. Good luck.

Mark

 

Hey Mark, thanks, that could be the insight I'm looking for - are you saying the front sway bar is on BACKWARDS?

 

I had the same problem too. I had the speed sensors replaced, but this time they were mounted on the inside away from the Anti-sway bar. The TRD front anti-sway bars were hitting the speed sensor cable. I also have the car lowered with Eibach springs and Bilstien Shocks.

 

wwest - seems logical to me that speed sensors would be involved in VSC. As I understand it the car looks at relative wheel speeds (if the car's going straight, all the wheels should be going at the same speed for example) and factors in steering angle and yaw to basically compute if the car is out of control, and from there, which wheel it should brake or whether the engine throttle should be adjusted to bring the car back under control.

 

pkeat - excellent - sounds like you've nailed it. Do you know where they mounted the sensor electronics (the encoder goes on the wheel as I understand it though)?

 

I'll get a picture up later. The part is not on the wheel. It's a little mounting bracket. Some of the blue paint on the anti-swaybar rubbed off on the clip holding the cable (the clip smashes the cable causing the vsc/abs lights to come on)

 

Sorry it took me so long to rely. My server was down. Pkeat is totally correct. We could not have described the solution to this problem better. We need to put this up on our Club Lexus Q&A.

Mark

 

Hmmm... I looked under the car and think I know what you're talking about now. I see a bracket attached to the strut and a cable clipped into the bracket running from the inside of the rim up out of sight. Anyway, I saw NO sign of damage to the cable on either left or right sides of the car. I sure do hope this is the source of the problem though.

Would LOVE to see your pictures if you have a chance. I'm taking my car in on Tuesday.