LX470 AHC & Steering - What's happening?

[rScotty]

How do I tell if the Automatic Height Control is working right on a 2007 LX470?.... Can't tell if mine is working right or not....

It rides right at low speed, & sits level regardless of load, but the steering seems twitchy at highway speed.

And unless the height change is real subtle, it doesn't seem to respond to the push button control on the console. It definitely doesn't automatically raise and lower when the engine is stopped.

But the ride is good & over all it takes bumps well and seems balanced - so other than the steering weirdness at high speed it's good.
I'm a pretty good old-fashioned mechanic, but out of date on this LX470.
My rude guess is that the AHC is somehow stuck in the lifted low speed position. Is there some sort of manual override? Fuse? Switch?
Thanks for any info, rScotty

 

[hankinid]

How do I tell if the Automatic Height Control is working right on a 2007 LX470?.... Can't tell if mine is working right or not....

It rides right at low speed, & sits level regardless of load, but the steering seems twitchy at highway speed.

And unless the height change is real subtle, it doesn't seem to respond to the push button control on the console. It definitely doesn't automatically raise and lower when the engine is stopped.

But the ride is good & over all it takes bumps well and seems balanced - so other than the steering weirdness at high speed it's good.
I'm a pretty good old-fashioned mechanic, but out of date on this LX470.
My rude guess is that the AHC is somehow stuck in the lifted low speed position. Is there some sort of manual override? Fuse? Switch?
Thanks for any info, rScotty

Try getting it to move with engine running, shift lever in Park, and emergency brake on.

hth

Steve

 

[Mxndrnks]

When is the last time you had an alignment? Twitchy at highway speed can be an alignment issue. Sorry, I cant help with the AHC....

 

[uHu]

The "Automatic" means that it will automatically keep the Normal height, regardless of weight/load/cargo/passengers, as long as it is within specs. You could notice height changes after stopping, as long as the engine is running and all doors closed.

The pushbutton is for Manual height control, and should work when standing still, w/o foot on brakes, wheels straight, all doors closed and engine running.

Steering might need an alignment.

 

[Brock]

unless newer models are different it does not lower and raise when you stop vehicle...here is how my 2000 LX worked:

LO- selected manually, lowers vehicle for loading, access for less mobile persons, or for parking in garage which was my favorite. Not to be used while driving...only while parked.

Normal- used for all driving, adjusts automatically for weight and speed as indicated and in coordination with the Comfort settings for all around ride....SPORT - Comfort

HIGH- for rough terrain driving....if vehicle detects you getting high-centered it can automatically lift another 2 inches to provide additional clearance. This is auto function based on wheel spin vs movement and is not manually selectable. Once you are moving it will return to HIGH position until you exceed 19 mph or whatever the amount is...then it goes back to NORMAL for street driving as you are entering street speeds.

A twitchy front end could also be because someone raised your front TB to get more lift on front. The vehicle likes a little rake from rear to front....and also ensure tire pressures are set according to panel on drivers door for front and rear. If the TB setting when empty and sitting flat is good...and tire pressures are good...and alignment is good. You dont want rear squatting as it will cause squirrely steering and other handling issues.

 

[Yukon LX]

Brock,

I dont think the front ends lifts when you crank the AHC torsion bar. It may go up very slightly, but all this really does is take some of the pressure off the front globes. I think the sensor would have to be move to lift the front more. I cranked my bars when i got the bull bar. very slight lift, but was told to do so to compensate for the new weight and pressure on the globes.

 

[agaisin]

Brock,

I dont think the front ends lifts when you crank the AHC torsion bar. It may go up very slightly, but all this really does is take some of the pressure off the front globes. I think the sensor would have to be move to lift the front more. I cranked my bars when i got the bull bar. very slight lift, but was told to do so to compensate for the new weight and pressure on the globes.

^^ Correct.

Height sensors are used to adjust height on the AHC.

TB adjustments on AHC are only used for one of two purposes:
1) neutral pressure adjustment (crank TBs to lower neutral pressure in front, back off TBs to raise neutral pressure in front)
2) if your front left and front right heights are not the same you use the TBs to level off. i.e. if front right is higher you can either crank up the front left tb or back off the front right tb.

I believe the average of the two front sensor readings is used to determine whether to raise or lower the front. Assuming your front is level front left to front right and you crank the TBs, your height will stay the same, just the neutral pressure will drop and vise versa.

Think of it this way - the TBs and hydraulics are working in unison to keep the height at the correct height sensor reading.
The more weight the TBs take (i.e. cranking), the less pressure is required to keep the front at the correct height; The less weight the TBs take (i.e. backing off), the more pressure is required to keep the correct height. The system will adjust the hydraulic fluid pressure to keep the height correct so the TB adjustments can't raise the front or lower the front.

 

[rScotty]

Try getting it to move with engine running, shift lever in Park, and emergency brake on.

hth

Steve

OK. I did that and it does go up and down. Thanks. So the system is working. Seems like I remember being in a 2007 LX470 and seeing it go down automatically when the engine was turned off and the driver's door opened to get out. Was I dreaming?
And was there ever a steering upgrade for the 2006?
rScotty

 

[uHu]

What a sweet dream.

There was a steering upgrade at some point, VGRS, Variable Gear Ratio Steering. Think that was from 8/2002 production.
There was an upgrade/recall to the VGRS as well - see https://forum.ih8mud.com/100-series-cruisers/402686-fyi-toyota-recall-39-000-2003-2007-lx470s.html

 

[Brock]

OK. I did that and it does go up and down. Thanks. So the system is working. Seems like I remember being in a 2007 LX470 and seeing it go down automatically when the engine was turned off and the driver's door opened to get out. Was I dreaming?
And was there ever a steering upgrade for the 2006?
rScotty

if it went down afterwards then he was losing pressure or the load and angle of parking area had it "readjust" itself.

if I remember right you had to shut the door before it would lower or raise....if you push button and exit right away to shut door with engine running it would do it...but engine off it should not move at all.

 

[Jim_Chow]

OK. I did that and it does go up and down. Thanks. So the system is working. Seems like I remember being in a 2007 LX470 and seeing it go down automatically when the engine was turned off and the driver's door opened to get out. Was I dreaming?
And was there ever a steering upgrade for the 2006?
rScotty

Engine has to be on to power the pump, speed < 10mph, foot OFF the brake pedal. I can't remember if the doors have to be closed or not. If you put it in low, it will automatically rise to N once you exceed like 9mph (IIRC, the manual says 25mph, but I think that's a typo). It will stay in high up to either 20 or 25mph until it reverts to N.