How to disable AHC from leveling? (Slee mod or ?)

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lexi4darin

lexi4darin

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Is there a way to disable the auto-leveling feature with AHC? There's a temporary "OFF" button on the AHC controls that would work perfectly if it stayed off. Mine always turns back on after 50mph (I assume this is a safety feature from the factory, :mad:)

I thought turning off the AHC might extend the life of the AHC system by putting less wear on parts. Maybe it would help me understand if the AHC was working properly since it fires up several times on every drive to level front and rear heights. It fires up so often I'm not sure the system is holding pressure; seems the front needs to be lowered or raised at least several times on a trip to work. As much as I like AHC, and I truly do love it, I just don't need to be leveled out so frequently. In fact, I'd rather have this feature off 90% of the time and just turn it on when the conditions require it.


Preemptively, the Slee mod , yes, I am aware of it. The Slee site is pretty specific that this electronic switch works to prohibit/interfere with height control (an override to factory conditions of when to control/manage vehicle height from L-N-H). But there is nothing indicating that it also affects auto-leveling, as in the front to rear or right to left.

If you know a way to disable the auto-leveling feature or you have more info about the Slee mod, please post. Maybe we need a Slee mod #2 for AHC ... anyone have an idea of the difficulty?
 
Sounds like your AHC system is already on it's way out.
 
because he dont know what ahc is :doh:


Toyota has build it, for been enabled everytime. So dont touch.
 
Why would you disable it?
 
I was curious on this as well. I just got a new to me 01 lx470 for my wife, and its awesome!
But stopping the AHC from auto leveling would be nice. As it does seem ridiculous some times to activate while sitting on slightly unlevel ground at a stop sign for example.
Anybody have the slee mod?
 
Sorry for the brief reply.

While the AHC will normally level the truck every blue moon, it's not normal for it to do it excessively. In my research, this behavior is typical of the system beginning to fail. Though that doesn't mean it needs to be replaced wholesale.

You might want to try to replace the AHC fluid and bleed the system. It may also be the height sensors.

Is your ride getting firmer and rougher? That might be indicative of a costlier issue which is the globes failing.

Turning the system off is definitely not the solution as it will begin taking on an unlevel posture.
 
I haven't noticed that mine is doing this.
 
I have the Slee AHC mod, and it does not affect the auto leveling. It 'locks' the system in whatever state it's currently in (H, N, etc), but the truck still auto-levels whenever it deems it appropriate...
 
ntsaint said:
I have the Slee AHC mod, and it does not affect the auto leveling. It 'locks' the system in whatever state it's currently in (H, N, etc), but the truck still auto-levels whenever it deems it appropriate...
Click to expand...

Thank you.
 
If the AHC is auto leveling excessively it might be worth getting your neutral pressures checked and it might be that it is too low causing the height to be affected more than it should by being on a slope etc? Cranking the T bars might fix that at the front.
 
If I can be so bold... I dont think Darin's AHC auto-levels more than spec... He's annoyed at the frequency and wants to take care of that, lock the ride height (ESP OFFROAD)... and by the way extend the overall life of the system by not having it level every 33.4 second (sarcasm).
 
Wildsmith, I'll check it out. Thanks for the tip.

And to Rob's point. It's not that "my" AHC levels too much, not enough, or anything other than it should according to design. It's just that I do'nt need to drive to the office in the morning and have the truck leveled several times. I can see where it's a safety issue. But there are circumstances when it's just plain excessive.

Off Road or on my 4 mile commute on mostly flat roads with 1 slight rolling hill that I encounter (at no unsafe speeds or road conditions), its just plain useless to be leveling the truck. There's nothing wrong with just driving to the office and maybe checking the level by leaving the system "on" once every week/two weeks or when your individual driving conditions require. I understand why Lexus builds in the dumby system but for those of us who don't lack common sense an override would be nice.
 
You could intercept the door open wire at the AHC ECU and run it through a two way switch to toggle between normal and forcing it to think a door is open. IIRC AHC won't height adjust while a door is open. Depends if the rest of the AHC programming cares if a door is open, hopefully not. I guess you could test this by driving with a door on the 1st catch so it isn't shut properly?
 
wildsmith said:
You could intercept the door open wire at the AHC ECU and run it through a two way switch to toggle between normal and forcing it to think a door is open. IIRC AHC won't height adjust while a door is open. Depends if the rest of the AHC programming cares if a door is open, hopefully not. I guess you could test this by driving with a door on the 1st catch so it isn't shut properly?
Click to expand...

Interesting. I wonder if this is the mechanism by which the Slee box works with.
 
I should have paid more attention when I had one but I think the Slee override intercepts the speed signals from the ABS ECU.
 
I'm going to order the slee mod and test some of your ideas Wildsmith. I'll do a write up then.
 
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