VSC and noise from under-carriage

[michael90630]

This Memorial Day long weekend we went camping in Utah and I drove my recently purchased 2007 V6, 4x4 4Runner. I also took our two bikes on Yakima full-swing bike racks. Total load of my camp gear, bikes, bike rack etc. would be approx. 300-350 lbs.

The thing that startled me is, I had to take a U-turn and drove off the paved 2 lane highway to the right side onto dirt and sand. All the wheels were on gravel/sand. The right side of the road was in a downward incline from the paved road. When I turned left and tried to drive up to the paved road, both rear wheels got stuck in the sand. Maybe because of the load of the bikes+rack and all the weight of the gear, the two rear wheel started spinning and dug in. This was not a surprise - can happen under these conditions (especially when in 2WD mode) and I knew I can get un-stuck by switching to 4WD mode.

However what really got me is, when both rear wheels started spinning and digging into the sand while I was trying to crawl up the incline back to the road, there was quite a loud quick succession of clanking noise from just underneath the vehicle. The VSC light was blinking but there was NO BEEPING! The more I stepped on the gas pedal the clanking noise continued.

To get the vehicle out, I engaged 4WD and locked the differentials. By design the VSC OFF light turned on and I got out of the sand in 2-3 seconds back onto the highway.

But the episode bothered me so much, I went back to the exact spot and tried the same thing again in 2WD. The exact noise came back with the VSC light flashing.

Is this normal behavior? It does not seem to me how VSC activates or warns the drivers. I have read the other threads in this forum regarding VSC activation, and it should only be some beeps until the situation is rectified.

Please note, before this episode, the day before, I had inadvertently drove maybe 1/4 of a mile with my emergency brakes applied. I heard the same clanking noise increasing in frequency with increase in speed. I very quickly realized my mistake released the emergency brake. Tested it on a uphill - fully pushed down and the vehicle held it's position.

So is the noise normal when VSC kicks in with both rear wheels spinning? Or something is broken because of my driving with the emergency brakes on having a domino effect on VSC? I would like to think the emergency brake system and VSC would be independent, but I am not an expert.

Any advise & suggestion will be appreciated. Depending on what I hear from you all, I am (reluctantly!) thinking of going to the Stealership to have them check it out.

Thanks.....

 

[Uneek]

I don't know if this will help you or not.

I was going up a steep incline driveway covered in ice (cause no one really stayed at the cabin and everyone else is too damn lazy to shovel or do anything to get rid of the ice). The drive way was about three car lengths and probably a 10-15 feet change in elevation from the bottom of the driveway to the top (not sure if this will give an idea of the steepness). I was in 4H with the center diff unlocked.

I never got the beeping from VSC or probably it's A-TRAC engaging, but I did get all the chatter and what sounds like a grinding sound along with a flashing light on the dash. I remembered the info I read on this site by Thai, I just keep my foot on the gas and held the RPMs at about 2k keeping the wheels spinning maintaining forward movement up the driveway. I could be wrong, but I think it only beeps if VSC is correcting the angle of the vehicle and "thinks" you might lose control.

 

[michael90630]

Uneek - thanx for your input. It sounds a lot like what I experienced. It's is kind of unsettling because I usually expect this type of noise when something is mechanically broken or wrong in a vehicle. However if this is "as designed" by Toyota I will have a sign of relief.

I am hoping others might post their experiences if they are similar to what we have heard.

 

[2003Can4runner]

you dont' have anything to worry about. A TRAC makes lotsa weird grinding sounds.

 

[Kmvreter]

What you experienced is normal. The ABS brake motor was cycling on/off and the trottle was probably auto cutting back to get you traction (A-TRAC.) The VSC light comes on when this happens. The beeping (plus lights plus ABS plus auto throttle back) only happens when you have forward motion, the ECU gets inputs from the wheels, steering and yaw sensors, and thinks you are in a skid that it wants to correct.
So much for the not-so-old days of correcting your own driving.
Enjoy the new ride!