Traction control problems

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).

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.