Max Speed for ATRAC? (1 Viewer)

[n55luvr]

Had my TRAC engage last night on the highway during an intense rain storm. Doing about 65. Happened a few times. Wasn't very intrusive at that speed compared to when I've felt it at low speeds offroading. First time I've seen it engage at anything over like 5 mph in the 7k miles I've driven it. At first I thought maybe a malfunction (I read the horror stories of a wheel locking at speed due to bad speed sensor) but then when I consider the conditions and amount of water on the road maybe it was a legit engagement.

Got me thinking, is ATRAC on all the time regardless of speed? I was also thinking that at those speeds maybe ATRAC tries to keep things moving in the right direction and then VSC only activates if ATRAC can't keep you in line?

 

[badlander]

Sounds like maybe you were on the verge of hydroplaning. Maybe you should slow down a little in that kind of rain.....

 

[n55luvr]

Thanks for the advice. Was looking more to understand what the speed thresholds were for ATRAC engagement. Some traction control aids are limited to certain speeds while other aids simply work all the time. I am not intimately familiar with the 100 series enough to know what those thresholds are.

In my case 1 of 2 things happened: 1 wheel had speed increase out of proportion to the other 3 thus ATRAC engagement. Else, I may have a bad wheel speed sensor and the heavy rain somehow caused the system to think I had 1 wheel rotating different than the other 3 and engaged erroneously.

Simply knowing if ATRAC is on ALL the time at ANY speed would help me easily understand what was going on behind the scenes. Maybe some members have experienced ATRAC at higher speeds as well, maybe out playing in the dunes or baja'ing on some fast desert trails.

 

[Ali FJ80]

yes I believe it is on all the time like a traction control system. when the roads are covered with snow here and I try to get it tail happy it kicks in with light blinking and then beeping and slows down the wheel or wheels that are spinning but it has never locked them up just enough to pull it back in line.

 

[n55luvr]

good feedback. I haven't owned this truck during the winter months so hadn't had any experience with it coming on other than very low speed, low traction situations offroad. Always worked wonderfully then and it sounds like it was working as advertised the other night in the rain soaked roads.

In my case, I am guessing I was hydroplaning like suggested above and the system kept me safe. Good stuff!

 

[soccernut]

I think you guys are confusing ATRAC with VSC.

ATRAC should not be engaged when you are in 4HI. It is a mechanism that allows more traction in stuck situations. It applies brakes to wheels which are slipping to transfer power to wheels which are gripping. I believe it will disengage at a certain point but I am not very well versed on that part of it.

VSC on the other hand engages at high speeds and also applies brakes in a different way to stop/limit your vehicle from going sideways.

 

[Bismarck]

^^^ what he said. Probably VSC not ATRAC.

 

[Hayes]

I think you guys are confusing ATRAC with VSC.

ATRAC should not be engaged when you are in 4HI. It is a mechanism that allows more traction in stuck situations. It applies brakes to wheels which are slipping to transfer power to wheels which are gripping. I believe it will disengage at a certain point but I am not very well versed on that part of it.

VSC on the other hand engages at high speeds and also applies brakes in a different way to stop/limit your vehicle from going sideways.

I'm relatively certain that ATRAC does function with the transfer case in high. I've seen it engage in my '05 LX (TRAC light, not VSC), and the conditions made sense for it to engage. I recall reading somewhere that programmed response and operating conditions vary between high and low range, but it does function in high range.

 

[Lowbudgetlc100]

slow down.........

 

[jLB]

At the speeds you're talking about, I sure hope it was VSC and not A-TRAC.

Having either one engage at those speeds (not to mention multiple times) is a hint that you are either driving too fast for the conditions or something is broken.

(Note to self: don't ever get in any vehicle N55luvr is driving)

 

[n55luvr]

You guys are killing me! I was driving down the highway with the flow of traffic, huge rain hits, water starts pooling on highway, TRAC lights up couple times then flow of traffic slows due to conditions. And so did I.

Was definitely the green TRAC light that came on a couple times at highway speeds. And there was a tiny bit of feedback through the steering wheel. Truck never veered of course so no need for VSC to ever engage. I like to think that if TRAC did not do it's thing and I did start to get sideways VSC would have then stepped in and self corrected.

I didn't say F it, it's a land cruiser I can go as fast as I want because ATRAC!

 

[Tom Cryer]

Thanks for the advice. Was looking more to understand what the speed thresholds were for ATRAC engagement. Some traction control aids are limited to certain speeds while other aids simply work all the time. I am not intimately familiar with the 100 series enough to know what those thresholds are.

In my case 1 of 2 things happened: 1 wheel had speed increase out of proportion to the other 3 thus ATRAC engagement. Else, I may have a bad wheel speed sensor and the heavy rain somehow caused the system to think I had 1 wheel rotating different than the other 3 and engaged erroneously.

Simply knowing if ATRAC is on ALL the time at ANY speed would help me easily understand what was going on behind the scenes. Maybe some members have experienced ATRAC at higher speeds as well, maybe out playing in the dunes or baja'ing on some fast desert trails.

In our 2000 LC 100, I've experienced what you experienced many times, but usually below 30 on snow and ice.

 

[ToHiHy]

Yes, TRAC does engage at HWY speeds. 4 high, no center diff lock. I get it often in the winter when there is black ice on my local mountain roads. I prefer to lock center diff more often now when the ice and snow is around. I find it overly intrusive and the programming in DRIVE and 4 high, cuts engine RPM aggressively.

 

[re_guderian]

ATrac question post #10

 

[RobRed]

@n55luvr / All ATRAC and VSC are all part of the same system.

Perfectly normal for ActiveTRAC indicator to light up and for Traction control to engage at highway speeds.

 

[Sandroad]

My owners manual has a good description of ATRAC and VSC operation in typical driving conditions, starting on page 145. The forum FAQs have a good description of ATRAC use off road. Sounds like the OP did the right thing and everything worked fine. I think the ATRAC and VSC programming on my LC are excellent. However, My Highlander Hybrid nannies are way too aggressive, with the vehicle having a mind of its own that I often disagree with.