2012 LS460L AWD erratic "coast down"
07-14-17, 08:44 AM
#1
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2012 LS460L AWD erratic "coast down"
Just bought my third LS... a 2012 LS460L AWD with about 50K miles. It's even better than the '90 and '99 LS's I had - which I drove for 310K and 275K stop-and-go Houston miles, respectively.
So I know how an LS should "feel". But there's something strange about the "coast down" on the 2012. For example: on a flat, level road at ~60 mph, I take my foot off the accelerator and let the car "coast down" without applying the brakes...
It smoothly decelerates until it gets to about 45 mph, and then it feels like the brakes are slightly on and begins to decelerate more rapidly. This lasts until it gets to about 40 mph and then it resumes a more gradual deceleration, as if the brakes were no longer on. And the cycle repeats at about 35 mph and again at about 25 mph. Each time getting a bit worse (ie, the deceleration is more pronounced each time). The engine revs don't seem to go up when the deceleration rate increases (at least the tach doesn't show increased revs).
Sounds like a minor problem, but it makes it difficult to drive smoothly in stop-and-go traffic. Is this maybe a problem with the AWD? I've heard that the AWD is extremely sensitive to tire diameters. I did notice that ONE of the tires was replaced by the previous owner just before they traded the car in. But all four tires are fairly new (definitely not the original set of tires).
So I know how an LS should "feel". But there's something strange about the "coast down" on the 2012. For example: on a flat, level road at ~60 mph, I take my foot off the accelerator and let the car "coast down" without applying the brakes...
It smoothly decelerates until it gets to about 45 mph, and then it feels like the brakes are slightly on and begins to decelerate more rapidly. This lasts until it gets to about 40 mph and then it resumes a more gradual deceleration, as if the brakes were no longer on. And the cycle repeats at about 35 mph and again at about 25 mph. Each time getting a bit worse (ie, the deceleration is more pronounced each time). The engine revs don't seem to go up when the deceleration rate increases (at least the tach doesn't show increased revs).
Sounds like a minor problem, but it makes it difficult to drive smoothly in stop-and-go traffic. Is this maybe a problem with the AWD? I've heard that the AWD is extremely sensitive to tire diameters. I did notice that ONE of the tires was replaced by the previous owner just before they traded the car in. But all four tires are fairly new (definitely not the original set of tires).
07-15-17, 02:51 PM
#3
Sounds like the AWD system vs transmission braking. Can you confirm? There have been some issue with the awd systems related to vibrations I believe. Some kind of super expensive fluid exchanges if I am remembering correctly. Well, expensive for fluid.
Last edited by Lexuslsguy; 07-15-17 at 03:01 PM.
07-15-17, 08:17 PM
#4
Try bumping it into Neutral before slowing down and see if that changes it. If the issue disappears, it is the transmission downshifting as you coast down. ECT Power mode will make the transmission behave like this.
07-16-17, 07:09 PM
#6
Lexus Fanatic
I think the difference in feel is the AWD which you aren't accustomed to. Give it a little time and you'll get used to it.
07-17-17, 06:15 AM
#7
none of the above...
I've had the issue with mine... (a 2012 AWD L)
It's a known issue at Lexus... the front drive shafts manufactured between specific dates affecting our 2012 AWD are not balanced properly, creating the vibration when coasting down from 70-60 to about 45. They need to change the faulty one(s) - both in my case.
The way to test it is to switch to neutral when it does it... if it disappears... that's the issue...
I've had the issue with mine... (a 2012 AWD L)
It's a known issue at Lexus... the front drive shafts manufactured between specific dates affecting our 2012 AWD are not balanced properly, creating the vibration when coasting down from 70-60 to about 45. They need to change the faulty one(s) - both in my case.
The way to test it is to switch to neutral when it does it... if it disappears... that's the issue...
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07-17-17, 08:21 AM
#9
Lexus Fanatic
Originally Posted by roadfrog
OP didn't say anything about "vibration". His symptoms seem like as explained by TEC80 , SW15LS and Scrutator......normal.
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