Traction control problems

You did not mention at what speed it happens. I am hoping it's not happening at slow speeds, such as 10-15-20 km/hr (10-15 miles/hour) Only when the sensor notices slippage is when it activates the traction control. Now for the same curve, if you "disengage" the traction control (or turn it to off), do you still get the same observations? I am asking because, the traction control nanny does not completely give up the control to you. So when you turn it off, and don't get any artificial slowing, you are driving in what Toyota would call in an acceptable way.

Just wanted to ask, how long have you been observing this? Has the tire got to do anything with it? How's the tread? Are you certain tires are not slipping? Have you tried changing tires to verify? Have you tried in curves in multiple locations at multiple times of the day? I am asking because, sometime seemingly innocent curves are not so innocent all the time, given slippery surface materials sometimes, such as cobblestones. Also, do you carry load above the roof? Stability control systems are a tricky business.

Again, I am certain you checked off all these already, but just wanted to make sure it's not the car that's giving you grief.

There wouldn't be any error code, because the car is "doing its job". Now if they have any blackbox.... It seems the traction control is acting too sensitive. Has it always been like this?

Toyota's Techstream system should be able to monitor stability control activity real-time. What I wonder is whether it would indicate the deviation between intended steering angle and what the yaw sensor is reporting. And I guess to make sense of this, you'd have to place an independent yaw sensor with it's own monitor in a similar position to see if the conditions that are invoking stability control interaction really make sense. You'd also want to monitor the individual wheel speed sensors, as they play a roll in determining if the vehicle is understeering or oversteering (sideways sliding changes wheel rotation speeds).

So some thoughts. I wonder if other worn suspension components impacts this? For instance, could bad sway bar bushings or bad shocks create more body roll than the system thinks is normal for a given turn? How about your tires? All matched and properly inflated? Any wheel that rotates more or less than the others could also be interpreted as 'sliding'. Good/even tread on each?

Does it always happen when turning in the same direction, or random? If there's a pattern, maybe you might experiment with inflation pressure slightly, or rotate your tires? Again if there's a pattern, maybe you actually need some offset in the zero point calibration (slightly towards the side with the issue).

Check out this solution! I have a 2004 with 170000 + miles. Steering seems fine. (It's not loose) Occasionally these cars illuminate the VSC light, ABS and engine light due to loose gas cap. After about 8 starts it just goes away.

My skid control has been kicking in at very predictable locations for several years now just like all these posted Sienna threads.

When I inflate the tires to 40 pounds the problem virtually disappears. Hmmmm.

One night after a fill up the magic ABS VSC and Check engine light decided to make an appearance again. No problem.

On the way home at one of the the usual places the traction and skid control lights and beeper went off.

This time, the brakes did not lock. The VSC was actually fully disconnected because of the "Gas cap" anomaly.

So...It's the VSC system computer sensors and or both. I don't know about you but, I know how to prevent my car from skidding.

How can I disconnect the Skid Control? ABS works just fine.

Thanks for reading and don't forget to inflate your tires to 40 pounds. You may get better gas mileage too!

Cheers

wnewton59 said:

How can I disconnect the Skid Control? ABS works just fine.

Click to expand...

A few people have looked into this, but the ABS and VSC systems are one and the same. It's just the triggering hardware and software that vary. The ABS pump system just takes commands and regulates pressure to the individual brakes. So any attempt to disable VSC will also kill your ABS. And that's something you really don't want to do....

Increasing your tire pressures serves to reduce the sidewall flex. Removing one degree of freedom helps to make up for unintended flex elsewhere in the suspension and steering system. It might not feel loose or worn to you, but if the tracking system is detecting and trying to act upon it, it's likely loose beyond design specifications.

As you've likely read elsewhere, 2004 vans were particularly sensitive to intervention, and there were a few TSB's guiding shops towards some updated components. You might check to see if you have the later released part numbers. Yaw sensor, IIRC? Junk yards are a cheap source for upgrades if you need them.

And I assume that you've check to be sure that there is no steering rack movement? Again, pretty common on these vans.