My wife called me this morning at work. She was driving to work and said the truck started feeling really bumpy as if it were jumping. No warning lights came on. I told her to pull over and wait for a while. When she started again, she couldn't replicate the issue. I told her to see if there was any bubble in any of the tires and she said no after checking. I just had my 5k service. Do any of you know what the issue could be? TIA

 

If the problem occurred early in her drive, maybe the parking brake was engaged??

 

-tell her to check all the lugnuts to make sure they are tight before she drives again.
-make sure the DAC is off, the t-case lever is in 4hi, center diff lock is off

those are the only things I can think of, good luck!

 

I would agree that it sounds like the button that locks out (locks into 4x4 mode) the slip coupling of the transfer case was inadvertantly engaged. That would bypass the torsion limited slip couplers and engage a fixed 4x4 locked config. It is HIGHLY recommended that the truck not be engaged in that mode on pavement. Only on dirt, mud or snow. Otherwise, the drivetrain could be severly damaged after a bit.
I am trying to remember what this button is called, but it is towards the front of the console near the aux power socket.

 

It's called the center diff lock

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X
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None of the buttons were pressed. Just a weird thing. I went in the evening and gave my wife my car and picked up the truck. I didn't feel anything out of the ordinary.

 

I believe the Center Diff Lock resets on power off/on. If so, you wouldn't find any buttons "pressed" when you got home.

Button is in horrible place and easy to accidently turn on with slight pressure (my wife kept putting her purse up there, and engaging it).

Not sure what you/she meant by "jumpy", but if she was going slow and turning in either direction the tires will squawk and jump.

My $5 says she accidentally engaged that button and it reset after her next stop.

 

Where is this button so I can show her and tell her to be careful for the future?

 

The button is just to the left of the controls for the heated seats and just to the right of the 12V/120W power outlet.

There is a picture and description on page 376 of the owners manual.

 

Putting that button right next to the driver side heated seat button, which must be turned on or off without looking while driving, was not a genius move on Lexus part!

 

If you have ever been in a 4x4 with locking hubs and non-slip axels, you would feel a rather accentuated jumping or "bucking" motion on hard pavement. This is especially true when your turnin the front wheels. Since the angles of the wheels are causing the back wheels to spin at different rates.

I for one am not that interested to find out how much the truck bucks in this mode on pavement. Maybe someone else wants to goof around with it.... I would rather rest assured my gearbox and differentials are not getting their teeth knocked out.

 

So if you press that button and it is on, then the light on the dash will lit up? I don't know if i'll damage anything, but mine is always on i guess. the light on the dash is on. Simply if that light is off, when i'm on pavement and turn my wheels, my car will actually jerk. So i've always had the light on. I don't know if i'm making any sense. haha. Hopefully somebody does and lets me know if i'm doing anything wrong. Thanks


calvin

 

Sounds like your light is backward.

 

The same thing happened to me shortly after I purchased my `04 GX470. I was driving the truck with the parking brake engaged. Everything was fine (and has been ever since) after I released the parking brake.

 

That does sound really backwards. Is the "VSC off" light also on? Locked diffs should shut VSC off (I don't remember exactly what it stands for).

Also - if you shift into 4WD low (via the second floor shifter) there is no telltale light on the dash! I was at the dealer and asked the service rep, and he told me of course there was. I had to bring it inside and show him. Then he said he asked someone else, and they said there is only a warning on the LX. So if you do drive in low, don't park that way or you might forget.