How should AHC function? (In the middle of a 24hr test drive and something seems off) (1 Viewer)

[uod]

So, I'm in the middle of a 24hr test drive on a 2015 LX 570. The AHC doesn't seem to function as it should. Is it true that the vehicle should be able to go from L to N and back when in park? Should I be able to drop it from N to L while driving? I feel like I got it to drop to L once, and then any time to try to do anything else the letter just blinks at me.

Let's say the AHC system is hosed. This car is coming from CarMax, and I understand their warranty to be pretty good. The only other thing I have found wrong is that rear hatch doesn't auto reply and stow. Immaculate service history from Lexus --- everything done at the proper intervals. Nothing skipped. Would you shy away from a vehicle with a non-functional AHC if you knew it had a warranty?

 

[AnyMal]

So, I'm in the middle of a 24hr test drive on a 2015 LX 570. The AHC doesn't seem to function as it should. Is it true that the vehicle should be able to go from L to N and back when in park? Should I be able to drop it from N to L while driving? I feel like I got it to drop to L once, and then any time to try to do anything else the letter just blinks at me.

Let's say the AHC system is hosed. This car is coming from CarMax, and I understand their warranty to be pretty good. The only other thing I have found wrong is that rear hatch doesn't auto reply and stow. Immaculate service history from Lexus --- everything done at the proper intervals. Nothing skipped. Would you shy away from a vehicle with a non-functional AHC if you knew it had a warranty?

When parked all modes are accessible given you are not depressing the brake.
Most modes are non selectable when in motion anyway so your normal there.

Put it in N in some flat ground fully off brakes without the parking brake engaged and it should quickly lower and relatively quickly get you into N and H modes.
I doubt theres anything wrong.

 

[lx200inAR]

The truck won’t go into Low at any speed higher than like 8 MPH. If you are going over 20 it won’t go into H assuming in 4HI diff gear. The L/H settings are not designed to be driven in normal conditions. They are for avoiding obstacles at lower speeds.

I would bet it’s unlikely that the AHC system is “shot”. It’s probably due for a fluid exchange and possibly new accumulator globes. Biggest concern is rusted hydraulic lines, but if it’s not sitting on the bump stops, you certainly dont have failed lines.

 

[uod]

Thanks to both of you! What you said makes sense. I know AHC fluid was changed out at the 60k interval as it should have been, and will be coming up on being due soon. If the globes end up being due soon -- are the globes considered a wear and tear type item? Or, something you would expect a warranty that covered suspension components to include?

Rusted lines are not much of a concern --- this is a southern vehicle and is spotless underneath.

 

[lx200inAR]

Thanks to both of you! What you said makes sense. I know AHC fluid was changed out at the 60k interval as it should have been, and will be coming up on being due soon. If the globes end up being due soon -- are the globes considered a wear and tear type item? Or, something you would expect a warranty that covered suspension components to include?

Rusted lines are not much of a concern --- this is a southern vehicle and is spotless underneath.

The globes are the primary gas charged part of the damper system. Definitely a wear item. But they generally don’t have catastrophic failure. There are people here who have put hundreds of thousands of miles on original globes. They are a relatively easy changeout for about $800 DIY. Probably not fun to find a shop to work on them. Just a reality that not many techs have worked on AHC, so it can be difficult to find places to work on them. A lot of good posts on this forum to demystify the system and keep it in good working order.

 

[highfructose]

There’s a button near your knee that disables the auto open and auto close function of the hatch. It’s easy to hit accidentally with your knee. You might check that if your hatch won’t automatically open and close.

From low, if you bump it to high, it should take 25-30 seconds to get into high if I remember correctly. Time it.

 

[TomEf]

For AHC, try all the heights at super low speed - like 5mph.

For the power lift gate, make sure the doors are unlocked. There are a few settings for the doors unlocking when you throw it in Park or when you open your door, etc. If the doors are still locked when you stop and want to pop the hatch, it will not open.

 

[EverywhereBear]

The chart in post #5 of this thread may help you with which modes work at what speed:

AHC for Baja style driving (LX Question) - https://forum.ih8mud.com/threads/ahc-for-baja-style-driving-lx-question.1199845/post-12987477

 

[uod]

There’s a button near your knee that disables the auto open and auto close function of the hatch. It’s easy to hit accidentally with your knee. You might check that if your hatch won’t automatically open and close.

From low, if you bump it to high, it should take 25-30 seconds to get into high if I remember correctly. Time it.

You were spot on ---- that button was pressed to disable the rear hatch auto close.

 

[AnyMal]

Globes are indeed a wear item IMO because they do age in springyness, but not according to Lexus or Toyota and are supposed to last the life of the vehicle.
In the case of your carmax warranty, a globe failure should be a warrantied claim.