Help with AHC Issue (1 Viewer)

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This is the only one I have. Here it connects to the tube running just infront of the rear axle. This connection is in front of the rear axle on the driver side of the truck and continues along the drivers side and connects to the height control valve which is right next to the exhaust behind a protective shield.

View attachment 2269031
That is a crazy amount of rust, given how clean the rest of the truck apparently is. There is a member on the 100 forum that is awesome with the AHC on the LX 470. I know the systems are different, but might be worth pinging him for another point of view. Former naval sub hydraulics guy.... Kept trying to convince him to buy a 570. ;)

Good luck and hope the new parts solve the issue, given how few AHC issues we see on the 570.
 
That is a crazy amount of rust, given how clean the rest of the truck apparently is. There is a member on the 100 forum that is awesome with the AHC on the LX 470. I know the systems are different, but might be worth pinging him for another point of view. Former naval sub hydraulics guy.... Kept trying to convince him to buy a 570. ;)

Good luck and hope the new parts solve the issue, given how few AHC issues we see on the 570.

Ya I dont get it. Idk what these tubes are made of that is different from all the other metal on the truck that is fine. It started its life in NewYork, but everything else is pretty clean other than these tubes.
 
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Went to the dealer and parts department is closed out here. Wanted to get eyes on to make sure I was ordering the right tube so I can replace it sometimes the height control valve. If anyone is bored and can help out i need the tube shown here that goes into the height control valve. I think its no.5. It's the tube on top in the circles section.

Screenshot_20200416-193635_Gallery.jpg
 
Check out parts.lexus.com for the parts diagram, much better than any parts department I’ve found.


as an aside - does anyone have a picture of the top of a rear Lx shock, where the AHC connects, through the gap In the wheel well if possible? Trying to make sure I’ve reinstalled the top nut down far enough
 
OK so update on this. I decided to take one more look at Techstream and play with a few things before I went to the work of replacing the height control valve and accumulator I bought. Also bought a suspension ECU thinking maybe that was an issue. Went into techstream and ran all the AHC tests again and they were all successful with the exception of the "raise front by accumulator" test which always fails because it just keeps lifting the front until the fluid pressure passes the threshold.

Anyway the big discrepancy I noticed was the Height Control sensor values were pretty far apart relative to other numbers I have seen shared on this forum. I checked to make sure the fronts were on the bottom of the bracket (sensor lift) and opposite on the rear. They were. So I then moved the FL sensor up the bracket and got it close to the value of the FR in Techstream. Once I did this the vehicle went thru LO MED HI without issue, even thought the sensors are clearly in different spots on the bracket. Took the truck for a highway drive and it drove kinda crappy. Took bumps worse than ever. In the screenshot below the sensors are back at the sensor lift position. All the other techstream numbers I've seen on here always show the height control sensor values pretty much the same for front and then same range for back, nothing like mine. Didn't touch the rear but you can see the Techstream value differences in the rears too. I measured the heights from center of the hub to the fender and the values were approximately 21.5" in the front and 24.5 in the rear. That seems to be inline with other numbers ive seen on here. So despite the height control sensor numbers being different the truck was leveling and creating the same hub to fender values on both sides. Anyone have any input on why this is? Are one or two of the sensors possibly bad? Is there a way to recalibrate the sensors with the suspension ECU or to reset the suspension ECU?

Capture.JPG
 
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Your rear seems really high. Mine is between 20 and 21". Your measurement would be what mine is in H mode . . . I looked again at that pic and I thought before you just had small tires, but no, your rear is super high.

It's an interesting data point that you can get full function by changing the front sensor offset. Have you already done the software height offset utility? Have you set the rear sensors physically full low? And then run the height offset to lower them more. You might get back the pressure you need that way.
 
Good point @grinchy . My stock rake at neutral height shows 1.75" between front and rear. Rake in high mode is 2.125".

Even after sensor lift (.75"F, .5"R), my rear in high mode only measures 23.625". 24.5" that you're measuring does seem to be too high for typical adjustments.

Measurements from center of hub to fender:
Front (lift)Rear (lift)
Stock AHC "N"19"20.75"
Stock AHC "H"21.0" (2")23.125" (2.375")
Sensor Lifted AHC "N"19.75" (.75")21.25" (.5")
Sensor Lifted AHC "H"21.75" (2.75")23.625" (2.875")
 
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Sorry my bad, those numbers i shared were in high. Normal mode just measured at approx 20" front and 21" rear. Still want to know why the sensor numbers would be so off.
 
I *think* the way to change the number is to zero out your physical sensor lift (go back to stock). Then go into techstream and run Height offset (level place).

Measure as indicated in the FSM, then enter those values. That should get the Height offset back to zero.

THen you can measure the fenders, decide how you want to adjust each corner, and re-height offset entry for the adjustments.

I found that height offset liked me to go up and down, and drive around the block. The before and after didn't really settle until I did that.

Then you remeasure and readjust until happy.

Then season with physical sensor lift if you need to.

This is only my experience, play with it and see if it will do what you want.
 
One common failure point on the 100-series is the height sensors. There doesn't seem to be many sensor failures on the 200-series, but that's where I'd start. Especially as you're seeing odd high readings in techstream.

I agree with @grinchy. If you're trying to solve in issue, reset everything to stock and restart.
 
Good point @grinchy . My stock rake at neutral height shows 1.75" between front and rear. Rake in high mode is 2.125".

Even after sensor lift (.75"F, .5"R), my rear in high mode only measures 23.625". 24.5" that you're measuring does seem to be too high for typical adjustments.

Measurements from center of hub to fender:
Front (lift)Rear (lift)
Stock AHC "N"19"20.75"
Stock AHC "H"21.0" (2")23.125" (2.375")
Sensor Lifted AHC "H"21.75" (2.75")23.625" (2.875")

TeCKis300 - do you have your post sensor lift "N" measurements for hub center to fender?
or am I misunderstanding your chart?
thanks
 
You're right. Added that detail to my original table and here.

Measurements from center of hub to fender:
Front (lift)Rear (lift)
Stock AHC "N"19"20.75"
Stock AHC "H"21.0" (2")23.125" (2.375")
Sensor Lifted AHC "N"19.75" (.75")21.25" (.5")
Sensor Lifted AHC "H"21.75" (2.75")23.625" (2.875")
 
You're right. Added that detail to my original table and here.

Measurements from center of hub to fender:
Front (lift)Rear (lift)
Stock AHC "N"19"20.75"
Stock AHC "H"21.0" (2")23.125" (2.375")
Sensor Lifted AHC "N"19.75" (.75")21.25" (.5")
Sensor Lifted AHC "H"21.75" (2.75")23.625" (2.875")
Awesome! Thank you.
 
Measure as indicated in the FSM, then enter those values. That should get the Height offset back to zero.

FSM Instructions are bonkers! There's a "standard Value in there" for the front and rear, but all you have to do is enter 2 values that are .1 apart.
1.0 and 1.1 or 4.1 and 4.2.
 

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