AHC performance questions, am I hallucinating?

[200 series]

Hello ih8mud World,

I am brand new to this forum (previously from expeditionforum.com), and already have burn questions with my 2-day old 2018 LX. I previously owned a 2016 LC, then switched to a 2020 Expedition, and then came back to this LX570.

I went to test drive a few LXs before getting this one and remembered that a different 18'LX had really different AHC performance compared to the one I got. I remember when braking to a stop, it would hold it's nosedive position and slowly level-out, making every complete stop like a chauffeur stop, no matter how bad I was on the brakes. Ours just bounced right up like a normal, passive spring system, similar to our previous Expedition. That one also seemed flatter around corners. The test drive was a long time ago, during the summer on all-seasons, rather than winter tires that is on my car right now, but I don't think that should affect much. I didn't go with that one, because it seemed neglected, parked outside for a LONG time and some wiring by the firewall seemed to had been chewed up, but no codes showing tho. The one that I went with was parked indoors, no rust, interior is our preferred colour, but slightly beaten up (can be cleaned). The biggest problem is that the BSM isn't working, because there is a hole in the right-rear bumper, alledgedly from a parking incident. The dealer promised to fix all of it, which they did, including replacing both of the radar modules. And so, a non-refundable deposit was put down before I did some research and found that the AHC pump is in that same right-rear corner . That said, we did test the height control during the test drive and it seemed to lower and raise fairly quickly, so Idk if the pump is really affected.

Can some fellow owners confirm that their AHC suspension performs like described above and that I'm not hallucinating, or suffering from buyer's remorse? Also, since the car is 6 years old, according to our beloved Car Care Nut, should I be doing an AHC fluid change at a Lexus dealer and hoping that it would fix "the problem" (if there really is one). Keep in mind, that around my area, there are really, really few LXs, so I'm not sure if my local Lexus dealer is aware, let alone have done such a service before. I believe it's not even stated in the owners manual, so I don't think a lot of people do it. If anyone knows a local AHC expert shop around Vancouver, BC, I would really love to know!

Sorry for all the rambling and thank you in advance for all your help and advise!

 

[2014 LEX 570 GA]

Hello ih8mud World,

I am brand new to this forum (previously from expeditionforum.com), and already have burn questions with my 2-day old 2018 LX. I previously owned a 2016 LC, then switched to a 2020 Expedition, and then came back to this LX570.

I went to test drive a few LXs before getting this one and remembered that a different 18'LX had really different AHC performance compared to the one I got. I remember when braking to a stop, it would hold it's nosedive position and slowly level-out, making every complete stop like a chauffeur stop, no matter how bad I was on the brakes. Ours just bounced right up like a normal, passive spring system, similar to our previous Expedition. That one also seemed flatter around corners. The test drive was a long time ago, during the summer on all-seasons, rather than winter tires that is on my car right now, but I don't think that should affect much. I didn't go with that one, because it seemed neglected, parked outside for a LONG time and some wiring by the firewall seemed to had been chewed up, but no codes showing tho. The one that I went with was parked indoors, no rust, interior is our preferred colour, but slightly beaten up (can be cleaned). The biggest problem is that the BSM isn't working, because there is a hole in the right-rear bumper, alledgedly from a parking incident. The dealer promised to fix all of it, which they did, including replacing both of the radar modules. And so, a non-refundable deposit was put down before I did some research and found that the AHC pump is in that same right-rear corner . That said, we did test the height control during the test drive and it seemed to lower and raise fairly quickly, so Idk if the pump is really affected.

Can some fellow owners confirm that their AHC suspension performs like described above and that I'm not hallucinating, or suffering from buyer's remorse? Also, since the car is 6 years old, according to our beloved Car Care Nut, should I be doing an AHC fluid change at a Lexus dealer and hoping that it would fix "the problem" (if there really is one). Keep in mind, that around my area, there are really, really few LXs, so I'm not sure if my local Lexus dealer is aware, let alone have done such a service before. I believe it's not even stated in the owners manual, so I don't think a lot of people do it. If anyone knows a local AHC expert shop around Vancouver, BC, I would really love to know!

Sorry for all the rambling and thank you in advance for all your help and advise!

Re: nose dive correction after coming to full stop, in my case it depends on how hard of a stop/how much nosedive is observed. I am pushing 150k miles and will be doing new globes (and shocks) in the next year or two, so I have been noticing more correction.

I think FSM says change AHC fluid every 60k, but if I were you I would do it regardless for peace of mind. Not very difficult and documented extensively in this forum.

 

[ryanCA]

according to our beloved Car Care Nut,

You will fit right in!!! He is the forum guru!


Curious question, why did you go from a LC to a LX?

 

[200 series]

Re: nose dive correction after coming to full stop, in my case it depends on how hard of a stop/how much nosedive is observed. I am pushing 150k miles and will be doing new globes (and shocks) in the next year or two, so I have been noticing more correction.

I think FSM says change AHC fluid every 60k, but if I were you I would do it regardless for peace of mind. Not very difficult and documented extensively in this forum.

Thanks for the reply! Sorry, I'm not too familiar with AHC terms just yet. Is the "nose dive correction" a feature of the AHC suspension, where it keeps the same nose dive angle under braking until 0 km/h, and then slowly levels-out by raising the nose when at a complete stop? Or is it the rebound effect (like in vehicles with passive suspension) that happened to my car when doing harder stops? I'm assuming it's the latter, because you are experiencing more "nose dive correction" as miles and age of your LX go up?

Also, what does FSM stand for? I think I will for sure get the AHC fluid replaced, but I wouldn't trust myself to do it and potentially mess up this complex and expensive system. I'm just contemplating whether or not to let the local Lexus dealer do it, because I'm assuming (emphasis on assuming, will have to ask them) that they haven't done that service before, cuz you would be surprised at how uncommon the LX is around here.

Please report back on how the AHC performs after the fluid change and all the maintenance!

 

[ryanCA]

Also, what does FSM stand for?

FSM for 200 series

Hello gentlemen, I am looking to download the factory service manual for 200 series. All links in the forum are "non-working". Please let me know where I can download the FSM, thank you so much in advance, Rafi Litmanovitz

forum.ih8mud.com

 

[200 series]

You will fit right in!!! He is the forum guru!


Curious question, why did you go from a LC to a LX?

The LC isn't available in Canada! So mad to find out about that after moving here, so we'll just have to settle with the LX here in the Great White North (eventho it's not even that cold here in Vancouver lol). Does your LX do the nose dive correction?

 

[ryanCA]

The LC isn't available in Canada! So mad to find out about that after moving here, so we'll just have to settle with the LX here in the Great White North (eventho it's not even that cold here in Vancouver lol). Does your LX do the nose dive correction?

Wife drives the LX, so I cannot tell you.

I only drive LC.

Makes sense. So you moved from the States to Canada and thus the LX? Gotcha! Are LX as dirt cheap in Canada as they are here?

 

[200 series]

Wife drives the LX, so I cannot tell you.

I only drive LC.

Makes sense. So you moved from the States to Canada and thus the LX? Gotcha! Are LX as dirt cheap in Canada as they are here?

I actually moved from South East Asia where I used to own the LC with the 4.6 V8. Moving here, I assumed the LC is also available, but nope, so decided to be adventurous and tried a domestic brand (not really domestic to Canada, but close enough). And boi was it an adventure with that 2020 Expy! Was a good car with GREAT power, but way to many QC issues and powertrain design flaws. The dealership was a pain to deal with, hence why I'm now having doubts with any dealership even if they're completely unrelated. Lexus should be good tho, hopefully!

So traded in the Expy and now back to a 200 series, but this time with a slightly more polarizing face. Well, you can't have everything, but at least I shouldn't need to visit and deal with the dealership that often! That said, the infotainment screen did glitch out on us once in the 2 days we owned it, cutting the screen and audio out completely. I just turned the audio dial off and back on again, and it fixed itself. Fingers crossed it's a one time thing.

Got our 2018 for around $48k US with 50k miles on it!

 

[2014 LEX 570 GA]

Thanks for the reply! Sorry, I'm not too familiar with AHC terms just yet. Is the "nose dive correction" a feature of the AHC suspension, where it keeps the same nose dive angle under braking until 0 km/h, and then slowly levels-out by raising the nose when at a complete stop? Or is it the rebound effect (like in vehicles with passive suspension) that happened to my car when doing harder stops? I'm assuming it's the latter, because you are experiencing more "nose dive correction" as miles and age of your LX go up?

Also, what does FSM stand for? I think I will for sure get the AHC fluid replaced, but I wouldn't trust myself to do it and potentially mess up this complex and expensive system. I'm just contemplating whether or not to let the local Lexus dealer do it, because I'm assuming (emphasis on assuming, will have to ask them) that they haven't done that service before, cuz you would be surprised at how uncommon the LX is around here.

Please report back on how the AHC performs after the fluid change and all the maintenance!

Take a spin through the forum and search is your friend. There is a deep well of knowledge on AHC here. Should be able to address any issues.

In the AHC system, the globes act as the spring and the shocks as the shock. As the system ages, the globes have more difficulty keeping the same spring rate and as such during stops the AHC is less able to correct for nosedive. So once you come to a full stop the AHC computer takes account of the shock heights and makes the correction that it was not able to make during the stop. Hope that’s helpful.

 

[2014 LEX 570 GA]

Also, everyone here (myself included) would highly advise against letting a Toyota/Lexus dealer service your AHC. The techs simply do not understand or care to understand the system.

I am relatively technically incompetent and was able to change the fluid in a friends driveway. Really not the hard to do over an afternoon if you read up and take your time with it.

 

[200 series]

Take a spin through the forum and search is your friend. There is a deep well of knowledge on AHC here. Should be able to address any issues.

In the AHC system, the globes act as the spring and the shocks as the shock. As the system ages, the globes have more difficulty keeping the same spring rate and as such during stops the AHC is less able to correct for nosedive. So once you come to a full stop the AHC computer takes account of the shock heights and makes the correction that it was not able to make during the stop. Hope that’s helpful.

I see, noted, thanks for the explanation! Will have to do a lot more reading.

 

[ryanCA]

I actually moved from South East Asia where I used to own the LC with the 4.6 V8. Moving here, I assumed the LC is also available, but nope, so decided to be adventurous and tried a domestic brand (not really domestic to Canada, but close enough). And boi was it an adventure with that 2020 Expy! Was a good car with GREAT power, but way to many QC issues and powertrain design flaws. The dealership was a pain to deal with, hence why I'm now having doubts with any dealership even if they're completely unrelated. Lexus should be good tho, hopefully!

So traded in the Expy and now back to a 200 series, but this time with a slightly more polarizing face. Well, you can't have everything, but at least I shouldn't need to visit and deal with the dealership that often! That said, the infotainment screen did glitch out on us once in the 2 days we owned it, cutting the screen and audio out completely. I just turned the audio dial off and back on again, and it fixed itself. Fingers crossed it's a one time thing.

Got our 2018 for around $48k US with 50k miles on it!

Welcome.

Lots of SE Asians on this forum.

Also you can connect with @Madtiger - his 200 info system also glitched out and he had many other issues. He loves his F150, which is basically same as your Expedition.

 

[ryanCA]

advise against letting a Toyota/Lexus dealer service your AHC. The techs simply do not understand or care to understand the system.

Really?!!!

 

[Ratchey]

Hello ih8mud World,

I am brand new to this forum (previously from expeditionforum.com), and already have burn questions with my 2-day old 2018 LX. I previously owned a 2016 LC, then switched to a 2020 Expedition, and then came back to this LX570.

I went to test drive a few LXs before getting this one and remembered that a different 18'LX had really different AHC performance compared to the one I got. I remember when braking to a stop, it would hold it's nosedive position and slowly level-out, making every complete stop like a chauffeur stop, no matter how bad I was on the brakes. Ours just bounced right up like a normal, passive spring system, similar to our previous Expedition. That one also seemed flatter around corners. The test drive was a long time ago, during the summer on all-seasons, rather than winter tires that is on my car right now, but I don't think that should affect much. I didn't go with that one, because it seemed neglected, parked outside for a LONG time and some wiring by the firewall seemed to had been chewed up, but no codes showing tho. The one that I went with was parked indoors, no rust, interior is our preferred colour, but slightly beaten up (can be cleaned). The biggest problem is that the BSM isn't working, because there is a hole in the right-rear bumper, alledgedly from a parking incident. The dealer promised to fix all of it, which they did, including replacing both of the radar modules. And so, a non-refundable deposit was put down before I did some research and found that the AHC pump is in that same right-rear corner . That said, we did test the height control during the test drive and it seemed to lower and raise fairly quickly, so Idk if the pump is really affected.

Can some fellow owners confirm that their AHC suspension performs like described above and that I'm not hallucinating, or suffering from buyer's remorse? Also, since the car is 6 years old, according to our beloved Car Care Nut, should I be doing an AHC fluid change at a Lexus dealer and hoping that it would fix "the problem" (if there really is one). Keep in mind, that around my area, there are really, really few LXs, so I'm not sure if my local Lexus dealer is aware, let alone have done such a service before. I believe it's not even stated in the owners manual, so I don't think a lot of people do it. If anyone knows a local AHC expert shop around Vancouver, BC, I would really love to know!

Sorry for all the rambling and thank you in advance for all your help and advise!

You might want to plan a trip South to the Seattle area. We have a few members there that can point you to reliable repair services if you are uncomfortable with the dealers in your area.

 

[200 series]

You might want to plan a trip South to the Seattle area. We have a few members there that can point you to reliable repair services if you are uncomfortable with the dealers in your area.

For sure, not far at all! Would love to make it our first road trip with our LX too!

 

[TeCKis300]

The "nose dive correction" feature on the LX is a secondary high rate spring on the front axle along with increased front shock damping. Most of which work to minimize nose dive in compression with perhaps minor rebound compensation.

Tires have a lot more affect than it would appear.

Weight transfer is also a factor in such a large and heavy SUV and it may be that you're driving it more aggressively now that you own it.

AHC is robust.

If it's changing heights correctly, the pump at the rear corner is working.

Drive it and enjoy it.

 

[200 series]

The "nose dive correction" feature on the LX is a secondary high rate rate spring on the front axle along with increased front shock damping. Most of which work to minimize nose dive in compression with perhaps minor rebound compensation.

Tires have a lot more affect than it would appear.

Weight transfer is also a factor in such a large and heavy SUV and it may be that you're driving it more aggressively now that you own it.

AHC is robust.

If it's changing heights correctly, the pump at the rear corner is working.

Drive it and enjoy it.

Thanks! Was thinking that it must be the tires too, can't wait to switch back to the all seasons. That said, as I read deeper into AHC stuff, I heard about the JDM programming for Japanese market LXs. It's from this thread: JDM LX570 AHC Programming? - https://forum.ih8mud.com/threads/jdm-lx570-ahc-programming.1350872/

Just curious, is there any more info regarding this?

 

[TeCKis300]

Thanks! Was thinking that it must be the tires too, can't wait to switch back to the all seasons. That said, as I read deeper into AHC stuff, I heard about the JDM programming for Japanese market LXs. It's from this thread: JDM LX570 AHC Programming? - https://forum.ih8mud.com/threads/jdm-lx570-ahc-programming.1350872/

Just curious, is there any more info regarding this?

Meh. What you already have is what you want. Prevailing speeds in the US are higher, and the system is tuned for domestic use. Don't get me wrong, it might be nice to personalize some parameters, but the system is already dialed nicely from the factory. The user selectable 3-position damper biasing and active response covers the broad spectrum of use cases well.

 

[Heckraiser]

In terms of braking nose dive, I still get it when braking hard. Usually after I'm stopped, the suspension will re-adjust itself and drop the butt noticeably.

But change your fluid, just to know it was done. Easy DIY, don't let the dealership do it. If you're not a DIY type guy, call around to various independent toyota/lexus shops and get a feel for their familiarity with the system.

 

[200 series]

Usually after I'm stopped, the suspension will re-adjust itself and drop the butt noticeably.

Yes! This is exactly what I'm talking about. I don't mind the nose dive at all so long as it smoothly and controllably levels out like you said after coming to a complete stop. I tried different drive modes to get it to do that, but the rebound (nose rise/butt drop) still feels somewhat fast and uncontrolled (might very likely be that I'm just driving it harder). Does your LX really rebound slowly and controlled where it significantly smooths out the harder stops, and to what extent do you feel the rebound effect?

But change your fluid, just to know it was done. Easy DIY, don't let the dealership do it. If you're not a DIY type guy, call around to various independent toyota/lexus shops and get a feel for their familiarity with the system.

Last resort would be DYI for sure! The hardest part is finding the right Toyota Guru around here. The good ones don't tend to show/advertise their expertise much at all, so a lot more looking to do!