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post #1 of 11 Old 03-25-2019, 11:08 PM Thread Starter
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A-Trac

I have a 2012 FJ 4X4 with a manual transmission. Prior to moving to Arizona, I lived in Colorado where I used my 2000 4X4 Tacoma for all of my off road driving and driving in snow. I didn't start driving the Cruiser as a regular vehicle until we moved to AZ. I don't live in the AZ mountains so driving in snow is not likely unless I make a trip to a higher elevation, which I did last week.


A few days ago, I had my first opportunity to drive on a snow packed paved road with a couple of inches of snow. I was in two-wheel drive. On several occasions, I would hear, mostly hear, a vibrating sound coming from the front. It could have been the rear but it sounded like the front. There was no steering wheel shaking or front end movement other than straight ahead driving. My tires are in very good condition. The sound would last a few seconds then disappear then return sometime later and again for a few seconds then disappear. I didn't see any lights on the dash but then, I had to keep my eyes on the road so I may have missed something.


Can someone explain what this is?


Just the other day, I learned what A-Trac does. I find the manual a bit confusing. On page 170, it addresses vehicles with two-wheel drive only. I need some explanation about A-Trac and the Auto LSD system. Again, the manual addresses Auto LSD but only for two-wheel models.

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post #2 of 11 Old 03-26-2019, 08:22 AM
GOT SN❄W?
 
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Could it have been your ABS kicking in? David K did a write up that goes into a lot of detail on trac and a trac here (post 2): https://www.toyotanation.com/forum/6...-trac-4lo.html


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post #3 of 11 Old 03-26-2019, 11:18 AM Thread Starter
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Moose, it could have been ABS, which was my firs thought but I was not braking when this was happening. I have experienced ABS in other vehicles on snow. This sound was completely different.
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post #4 of 11 Old 03-26-2019, 06:13 PM
GOT SN❄W?
 
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Then Iím at a loss. I would think VSC but that audibly yells at you.


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post #5 of 11 Old 03-27-2019, 11:24 AM Thread Starter
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Moose,


I'm sorry for the fuzzy memory on this. As I said, I do know I was not breaking when this happened but I believe I let off the gas each time. I think slowing the FJ and the stopping of the noise is coincidental. Each episode would last maybe ten seconds or so. I don't think I applied brakes. Could this have been ice built up in the front brake calipers?
My snow trek on the paved road to lower elevation was about 25 miles. Upon reaching lower a elevation and way less snow on the road, it did not happen. A few days before this, I pulled a stuck vehicle from a mud bog. It wasn't a really bad situation so I could have probably done this in two wheel drive but I went to 4L. This was done in reverse for a distance of about 20 feet.


I will go to a Toyota dealer and pick some brains.
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post #6 of 11 Old 03-27-2019, 11:32 AM Thread Starter
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Moose, A couple more points. Mileage on the Cruiser is about 45,000. Brakes and front rotors were replaced about one year ago because I was getting chattering while braking at highway speeds.


I used the Cruiser to pull three heavily loaded U-Haul trailers (different trips of course) from the Denver area to Gilbert, AZ. The route we took from Payson, AZ to Gilbert (AZ Highway 87), about 80 miles, has several long somewhat steep hills. Braking was required on the downside of these hills. These trailers have their own braking system but I am sure the rotors took a beating. The new rotors are the ones with holes for ventilation.
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post #7 of 11 Old 03-27-2019, 10:08 PM Thread Starter
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I consulted my mechanic. He said it is the ABS. I agree. So I decided to check the owner's manual. ABS is found on page 173 but there is no mention there of the ABS and I can't find anything else in the book about it.
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post #8 of 11 Old 03-29-2019, 10:47 AM
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Thatís why I said VSC. If you were not touching the brakes, then it was most likely the stability control kicking in which uses the brakes (and ABS). If you were touching the brakes, then ABS is the obvious source of the sound (which would be normal...and would then lead me to say itís all about your tires like type, tread depth, etc). The ABS will kick in a lot with poor tires for snow conditions.


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post #9 of 11 Old 03-29-2019, 11:47 AM Thread Starter
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Moose, your explanation sounds right. I was not using the brakes. My tires are a bit on the aggressive side and have fewer than 5k miles. Thanks again.
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post #10 of 11 Old 03-29-2019, 11:48 AM Thread Starter
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As the mechanic said, the system is smarter than drivers.
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post #11 of 11 Old 03-29-2019, 12:09 PM Thread Starter
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Moose, the attached You Tube video is exactly what you said and what I experienced. The video instructs how to disable the VSC in earlier models. I don't care about that because my Cruiser has a disable button on the dash. At the beginning, you will hear exactly what I heard.
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