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I've owned my '01 4Runner since new, and am familiar with how/when/why the VSC system kicks in. The truck has been on numerous sets of 32" tires since 2003 or so, and spent about 400,000 miles riding along on '99 tall coils, 1" rear spacers and a few sets of Bilsteins.
A few months ago I decided to refresh the aging suspension (truck now has 507,000 miles) and replace springs/shocks/strut mounts/all body mounts/steering rack/lower control arm bushings/front upper control arms, etc., etc. This went on over a few months, using a new Toyota rack, Dobinsons IMS ~2" suspension, SPC upper arms, Eimkeith panhard correction bracket, etc. After a proper alignment and a new set of 265/75/16 TerraGrapplers, the truck rides great and rolls super smooth.
But - the reason for my thread is that the VSC has become ridiculously sensitive. So much so that merely taking 40mph curves near my house will cause the VSC 'skidding' symbol to illuminate and the the beeper to sound. In the past, I could cause it to sound off by taking corners far too fast. Fair enough. But the level of sensitivity now is nuts.
This morning I followed the VSC zero point calibration procedure VSC calibration exactly as written, took the truck for a spin, and found that there was no change whatsoever. I have a tough time believing that an additional inch or so of suspension height would be enough to send this system into spasms.
So, I'm hoping someone here has gone through a similar exercise and can offer some pointers. I'm wondering if things like steering angle sensors, yaw rate sensors, etc. can simply go bad.
I'm not super familiar with the VSC and TRAC systems as my '99 aren't that smart. What is the input sensor for the system? ABS tone rings? Yaw sensor? Is it possible that one of your ABS sensors is either losing magnetism or has filings on the contacts mimicking Hull? If it's a yaw sensor somewhere, is it possible whatever bushings hold it in place have degraded or that sensor has been contaminated or compromised?
I'm not super familiar with the VSC and TRAC systems as my '99 aren't that smart. What is the input sensor for the system? ABS tone rings? Yaw sensor? Is it possible that one of your ABS sensors is either losing magnetism or has filings on the contacts mimicking Hull? If it's a yaw sensor somewhere, is it possible whatever bushings hold it in place have degraded or that sensor has been contaminated or compromised?
Fan,
Thank you. My understanding is that the VSC system uses the ABS sensors, a steering angle sensor, a yaw rate sensor, and possibly an acceleration sensor.
- With respect to the ABS sensors - I could pull them and see what I find, but would they not throw a fault code during normal operation if they were in any way compromised?
- The steering angle sensor is at the top of the steering column, directly under the cover, and the yaw rate sensor is under the center console/cubby (I believe). Used ones can be picked up for cheap on EBay.
If I'm going around a curve and VSC flashes & beeps, a quick twitch of the wheel away from the turn usually kills the silliness.
The truck drives better than it has in many years, so it would be nice to find a solution.
Just thinking back to when I was tracing down my transfer case actuator issues, the position sensors on the front diff would signal either open or closed at the poles (like they should) but somewhere in the range of the plunger, when they should have continuity, they would lose it for a millimeter or so and that would cause the 4wd ECU to error.
My next investigation in your issue would be to check those sensors for continuity across the full range of tilt of the sensor. Maybe there is a dead spot in there an the ECU isn't smart enough to realize its bad information.
Trying to get in the mindset of the Toyota engineers if you will.
Update: I also have a 2002 4Runner, identical to the 2001 in all respects. A few weeks ago I pulled the yaw & deceleration sensors from the '02, installed in the '01, and calibrated. Zero change.
At this point I had already purchased used yaw & steering angle sensors on Ebay.
Today I installed the replacement sensors, calibrated, and took a test drive. Zero change.
Then I pulled each ABS sensor, one after the other, and cleaned them. Nothing looked out of the ordinary. Another test drive, zero change. Going into slow curves near my house immediately makes the VSC wake up.
- ABS works correctly
- TRAC works correctly (even though I have no use for it)
- Center diff lock goes in & out correctly
- 4WD works perfectly
- The calibration procedure works correctly (but doesn't change anything).
To close the loop on this frustrating issue - after replacing the yaw & steering angle sensors, swapping in a known-good deceleration sensor and a known-good TRAC/VSC ecu, checking & cleaning all four ABS sensors, and calibrating the systems 6,438 times, I decided to rid myself of TRAC & VSC for good.
I left all sensors & the ecu in place since the ecu probably influences other things as well. Then I completely removed the old AndyMod and located the red/black tracer wire for the AndyMod 2.0. Peeled back some loom tape, snipped the wire and terminated the ends properly.
The last step was to pull the instrument cluster and remove the TRAC & VSC bulbs.
End result, I can drive through curves at normal speeds again without constant electronic oversight. Finally! The ABS continues to function as it should, the truck goes in & out of 4WD correctly, and the center diff lock still engages.
May 21, 2022 | 08:06 AM
