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Traction Control Activates on S curves

4179 Views 3 Replies 4 Participants Last post by  hutzi69
I live on a curvy country road. All of the sudden traction control now activates on the S curves that I have been driving for years at the same speed, etc. Shocks, etc. seem fine, but this new problem is quite annoying! Any ideas how to diagnose/repair?
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Check the tires? Even if they have the tread, the treads may also have lost their rubber grip and could have become hard brittle.
Tire slippage causes traction control to activate. Start by rotating the tires back to front. Any improvement/difference? If so, its time to get new tire sets.
What exactly is happening? Is the "slip indicator" in the instrument cluster lighting up? Is the engine output being automatically reduced? Are brakes being automatically applied? Are you skidding?

What is the road surface of your country road like? Gravel? Recently oiled?

I assume that you have verified that your tire pressure is correct - 35 psi or a little more in all tires - but I would think that your TPMS warning light would be on if that is the problem assuming that you have a working TPM system.

Traction Control and Vehicle Stability Control work together. They are complex safety systems and not something that most amateur mechanics can repair when there is a problem. One of the causes of a TRAC problem can be a defective ABS sensor. At the heart of VSC is a module that includes a gyroscope - I assume it is in the floor at the center of the Sienna like on the Lexus vehicles I'm more familiar with.

As a temporary measure (after checking tire pressure), you could see what happens if you turn off TRAC or both TRAC and VSC. Press the TRAC off button on the dash quickly one time to turn off TRAC (the TRAC off indicator in the cluster will light up). Press and hold the TRAC off button for three seconds to turn off both TRAC and VSC - both the TRAC off and VSC off indicators in the cluster will light up.

If you can't figure out this quickly, I recommend that you take this problem to a Toyota dealer or a knowledgeable indie repair shop ASAP.

Is always good to provide the model year and trim (LE, XLE, etc.) of your vehicle although in this case the only trim that has a different TRAC/VSC/etc. system is the Limited with Advanced Technology Package.
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Hi, I'm from Germany and my dealer has no repair guide for the Toyta Sienna: So maybe is there so to help me:

Where is the control modul for the tire pressure warning system? The yellow light is always on and the mechanic cannot find the control modul to inactivate it.

Thank you so much for helping!!

Wolfgang Hutzler
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