LX570 AHC “Basics” - Added as sticky thread for AHC Issues (1 Viewer)

[longranger]

Point of this thread is to serve as a repository for 200-series AHC info, including LX570 and LC equipped with AHC (in select global markets).

Let’s begin with a theory. The 200-series LC (without AHC) and the LX570 (or LC with AHC) are like New York & LA. LC “purists” are like New Yorkers, going on and on about the virtues of “tried and true” spring setups, but in order to enjoy their springs, they seem to have a need to talk some smack about LA/LX with its “over-the-top” hydraulic suspension, “unnecessarily complex” design, and high “cost of repair.” New Yorkers, in other words, make a hobby out of kicking LA in the shins.

LA folks, on the other hand, try to emphasize how similar LA is to New York — how similar the capability of the LX570 is to the capability of the non-AHC “cruiser” — we all know this anxiety LX folks have when they pull up next to a Land Cruiser. “One is a proper ‘off-road tank;’ the other is a ‘mall cruiser.’” But once LA/LX folks get over their anxiety, you don’t really hear a lot of “New York” bashing. There are differences and similarities, but LX folks are like Angelenos, they seem to be out enjoying their AHC-levitating rigs. After a ten-year model run, there don’t seem to be the catastrophic tales of woe we all imagined were “just around the corner”.

With a decade under its belt, it may be time to admit that the LX570 AHC system is just brilliantly engineered and built, working well across a dizzying range of climates, terrains, and rig stresses.

Below are some links to tech basics (including excellent schematics and repair guides). There is far too much new terminology and technical jargon to try to do anything like a “glossary” on AHC parts, and there’s been some confusion even about what to call the shocks/struts on the LX, given that they are hydraulic and come with so-called “actuators” — so rather than do that, what I learned is that it’s just easier to start familiarizing yourself with the diagrams and peeking under the running boards, to get a sense of how this part of the machine is supposed to work:

REAR SUSPENSION REAR SUSPENSION: REAR SHOCK ABSORBER: INSTALLATION (2008 LX570) (courtesy of another thread on this forum, can’t remember which)

There are a few links I’ll need to look around for, and will post as comments to this thread. There’s a 40-page .pdf floating around somewhere that attempts to explain the inner workings of the AHC, and it’s dense stuff. Some of the most candid assessments by mudders are those that are from folks with engineering backgrounds and so on, who write that’s basically, this stuff is “over our heads.” A lot of that probably has to do with the electrical engineering / coding that runs the whole system, specifically auto-leveling programs, load-balancing programs, traction-control programs, etc. It’s complex machinery, like a top-of-the-line Seiko watch.

Like that Seiko watch, what we all expect from the AHC is smooth & consistent operation. That only comes with time and trust in a particular rig after progressively rougher exploitation. In a separate comment, I’ll share some of the things I did in order to build up trust in the suspension components, and it’d be valuable to hear advice from mudders who bought into the 200-series AHC trip, especially when buying used —

1. How would you recommend prospective buyers test the system during their pre-purchase inspections?
2. What are good post-purchase “preventative maintenance” suggestions for folks who are new to 200-series AHC?
3. What are absolute “No-No” suggestions, in other words, mistakes you might have made that you want others to avoid making.
4. Etc.

Below is a schematic that shows fluid leak weak spots or “junction spots” — whatever you want to call it, but areas that Toyota mechanics identified on a schematic, so probably a good starting point for visual inspection purposes.

If the AHC-equipped rig you’re looking to buy is leaking suspension fluid from these spots, chances are, you’ll be learning a LOT about hydraulic suspensions in the coming months/years. For most folks, this will mean “run!” For others, it can signal opportunity.

 

[grinchy]

 

[longranger]

Here’s a rather unusual but really reassuring step I took when I was trying to split that really narrow hair in my decision between a more-traditional non-AHC Land Cruiser and the, surprisingly, cheaper LX570 (when controlling for other objective factors in the used car market, such as mileage, previous history, etc.) — I actually paid $500 for a set of front and rear accumulator globes on EBay so that I could examine them more closely.

My reasoning was simple: although the suspension hydraulics seemed well-shielded from mild LATERAL hits by the aluminum running board and from bottom hits by the steel slider-like piping, I still wanted to “feel” and examine the metal globes and connectors in a way that would give me a deeper appreciation and peace of mind for the engineering. Plus, if the parts needed to be replaced (I also had salt corrosion on contact points), I’d have the parts. Lastly, seller had agreed to pay — so I’d be getting potential replacements “free.” Not really free bc I’m paying overall, but you know what I mean.

Conclusion, examining separate suspension components when installed is difficult on any car, not to mention the AHC, which is probably—without exaggeration—the most advanced suspension setup in any passenger-oriented production vehicle. You can’t just “take out” an “accumulator globe” from your LX to see if it’s “alright” and then plop it back in. To do that, you’d need to bleed the hydraulic fluid and be VERY careful when disconnecting rusted/weathered/corroded/dirt-fused connectors. For me, the risk of potentially screwing up an apparently well-balanced setup was not worth it.

Here’s another point — I took the vehicle in to the local Lexus dealer and had it examined top to bottom by a mechanic I came to trust. The request to the service department was simple, “would you trust this specific truck with ferrying your kids on a daily basis and also over treacherous overland terrain?” — and suspension-related, “seller has agreed to pay for all suspension work, what do you recommend be done.”

Everyone knows that last part is a rare event. I was prepared to have the service guy jump at the opportunity, suggesting a total overhaul or “repair and replace” (which would have been warranted by corrosion of certain components). Their position was simple, “Yes, there’s some corrosion, but if it ain’t broke, don’t fix it!” The mechanic, apparently worried that the service manager would still try to make a repair suggestion where one wasn’t warranted, took the extraordinary step of pulling me aside and emphasizing that in his experience with the LX, it’s a really well-built and the entire service department had ever done a “handful” of LX suspension fixes. I asked how many and the answer was “one or two” over the last ten years. He pressed the point, “I inspected and drove it; all works well; if and when something fails, then let’s do work on this truck...in my view, anything at this point would just be unnecessary.”

That level of confidence in one’s machinery is really trust-inspiring, and I’ve been driving the LX in very different manners and styles since. On certain days i experiment with different H/N/L and Sport/Normal/Comfort height/dampening levels, at different speeds and different road conditions. I have the “kneel”/“auto-Low-to-Exit-Vehicle” setting activated, which is another way to make sure the system is working well. I do these on different inclines, different ignition timings (turning off motor in the midst of a raise or a lower, just to “troubleshoot” but really more to just learn and admire the capabilities of the system). In all, after a month of driving the LX across different road/off-road conditions, I’ve been extremely impressed with the build and capability of the AHC.

A lot of this is subjective impression, like admiring an aftermarket camshaft or piston that’s never been installed in an engine, and may never be installed in an engine. But that’s not the point. A lot of the fear that many folks have about the AHC is subjective fear — wondering, like I did, “what happens if I buy this expensive rig, and the suspension breaks down on me in the middle of nowhere, and I have no idea how to troubleshoot hydraulics?”

I’ll answer by invoking the wisdom of the Lexus mechanic who dissuaded me from installing suspension parts where the parts and service cost was going to be covered by a third party — “if it ain’t broke, don’t fix it.”

And, in response to my question about “corrosion leading to higher chance of failure...?” his words were, “We’ll cross that bridge when we get there.”

Aside from the word “warranty,” what helped you overcome any initial reservations about AHC when buying your AHC-equipped 200?

 

[longranger]

Top two photos are dealer-lot photos of accumulators on a 2018 LX570. Bottom three are of the accumulators I bought on EBay, which were supposedly from a 2017 LX570.

This was another reassuring point in my learning curve, because it showed that Toyota has apparently kept the AHC system unchanged

 

[longranger]

Top two photos are dealer-lot photos of accumulators on a 2018 LX570. Bottom three are of the accumulators I bought on EBay, which were supposedly from a 2017 LX570.

This was another reassuring point in my learning curve, because it showed that Toyota has apparently kept the AHC system unchanged

Point being, if it ain’t broke, don’t fix it. If I am missing some key suspension/AHC innovation that Toyota introduced, or if there were changes to the AHC “plumbing” that were made over the past decade, please share what those were.

In the meantime, here’s more AHC “visual stimulation” (images not mine, originally traced to Toyota/Lexus in marketing materials — used here in a fair use and strictly educational context).

 

[tbisaacs]

Anyone else see it?

The 570 has arrived The GX470 had a similar moment a few years ago and the aftermarket finally caught up.

 

[TonyP]

Anyone else see it?

The 570 has arrived The GX470 had a similar moment a few years ago and the aftermarket finally caught up.

Yes. We've officially reach the AHC tipping point...

 

[FinallyGotOne!]

Thanks for the post, Longranger. I like the idea. I've had AHC-equipped LXs for almost 14 years now and have not had one AHC-related problem and I do not cruise malls - I use the heck out of my trucks.

That said, I do ensure I follow the maintenance schedule for AHC service. I do the flushes myself and they are not any more difficult than a brake system bleed, which I also do according to The Book. That's probably the only post-purchase preventive maintenance that is necessary.

In the spirit of creating a repository, below I pasted a comment I posted elsewhere a while back regarding why I think AHC is just fine. It may contribute to the value of this repository if someone is trying to decide if they should avoid AHC...

----------------

So I'm going to throw in my two cents: "It's all about the requirements". The question regarding which suspension system is better can't be answered without first addressing what the truck will be required to do, for how long, and at what cost. The obvious extreme is the racing example. The system must perform at high speeds in very challenging conditions only long enough to win, and cost is not a limiting factor.

In the passenger market, the design-to conditions are less challenging, the system has to last 25(?) years, and the cost has to be competitive. Toyota has assessed, at least for now, that the LC market requirements are best answered with KDSS and the LX market with the AHC.

If you back into it, I think you'll find that both systems are perfect for a certain set of requirements. For example, here is why the AHC has been perfect for me for the past 14 years:

-- We do five or six long trips a year. Comfort is important on the way to whatever we will be doing, whether it is visiting family for Christmas, or four-wheeling into Park County.
-- We tow a 6000 lb boat and a 3000 lb enclosed trailer. Self-leveling and variable damping is important.
-- We need to get to mountain biking and hiking trailheads, hunting spots, and medium-difficulty off-road trails and raising the truck often mitigates risk of damage.
-- We have older parents who appreciate ease of entry when the truck is down.
-- We carry cargo now and again and I appreciate a lower truck when I am lifting something heavy in or out.
-- Back to towing: I am spoiled in that I can save time cranking the trailers up and down to ball level by raising and lowering the truck instead.
-- We hate washboard...and AHC almost eliminates it!
-- I do my own preventive maintenance and don't mind flushing the AHC according to the Toyota schedule.
-- We don't drive high-speed off road.
-- We don't purposefully leave the ground(!)
-- We don't rock crawl
-- I may get the itch once or twice a year, but I probably won't ever put sliders on my 570
-- *** The fact that I can't put Slee bumpers front and back and still maintain my stock cargo and towing capacity doesn't bother me a whole lot...just a little. Well, more than a little, but I've traded away that requirement and can live with it.
-- If it ever does fail, the chances are exceedingly low that I will be somewhere very far off road.

Bottom Line: For my requirements, AHC is perfect and Toyota's execution has been perfectly reliable and effective on both my '00 LX 470 and '11 LX 570.

 

[TeCKis300]

Great post. Love the pics of the AHC components. It looks like space ship stuff compared to even the most sophisticated aftermarket suspensions.

I fondly remember this post back in the, I'll call it "before AHC" times, back in May 2017.

This has been a good discussion all around for understanding and awareness between the two platforms. Having been on the boards for a long time, since the 100-series days, there's general misconception and mistrust about AHC, especially those that have not used the capability. It's been the same progression for the LX470 and it's taken work in the earlier years from my part and others to bring that community around. Now you see tons of LX470 owners who eagerly modify and augment their AHC suspension for various applications, not unlike one would do with the LC. Then there's those that ripped out their AHC, only to then finally understand what they gave up!

I'll be the first to acknowledge that AHC is not for everyone. But at the same time, that's usually the exception for the extreme users. Plenty of hardcore users now take advantage of AHC for the LX470.

The biggest benefit of AHC is its dynamic adaptability for a multitude of scenarios. Static suspensions are generally optimized for specific use cases. Sure you can adjust coilovers, but not on the fly. If ICON, for example, offered a dynamically adjustable (height, spring rate, and damping), remote reservoir coilover, that went 200k+ miles between rebuilds, I think that surely would catch peoples attention. Not only does it exist, but Toyota has engineered it right into the LX570. Because no aftermarket vendor has the technical chops (not overstating this) to build something as sophisticated.

 

[longranger]

Yes. We've officially reach the AHC tipping point...

Nice play on words; sure hope I don’t reach the AHC’s tipping point.

 

[longranger]

Thanks for the post, Longranger. I like the idea. I've had AHC-equipped LXs for almost 14 years now and have not had one AHC-related problem and I do not cruise malls - I use the heck out of my trucks.

That said, I do ensure I follow the maintenance schedule for AHC service. I do the flushes myself and they are not any more difficult than a brake system bleed, which I also do according to The Book. That's probably the only post-purchase preventive maintenance that is necessary.

In the spirit of creating a repository, below I pasted a comment I posted elsewhere a while back regarding why I think AHC is just fine. It may contribute to the value of this repository if someone is trying to decide if they should avoid AHC...

----------------

So I'm going to throw in my two cents: "It's all about the requirements". The question regarding which suspension system is better can't be answered without first addressing what the truck will be required to do, for how long, and at what cost. The obvious extreme is the racing example. The system must perform at high speeds in very challenging conditions only long enough to win, and cost is not a limiting factor.

In the passenger market, the design-to conditions are less challenging, the system has to last 25(?) years, and the cost has to be competitive. Toyota has assessed, at least for now, that the LC market requirements are best answered with KDSS and the LX market with the AHC.

If you back into it, I think you'll find that both systems are perfect for a certain set of requirements. For example, here is why the AHC has been perfect for me for the past 14 years:

-- We do five or six long trips a year. Comfort is important on the way to whatever we will be doing, whether it is visiting family for Christmas, or four-wheeling into Park County.
-- We tow a 6000 lb boat and a 3000 lb enclosed trailer. Self-leveling and variable damping is important.
-- We need to get to mountain biking and hiking trailheads, hunting spots, and medium-difficulty off-road trails and raising the truck often mitigates risk of damage.
-- We have older parents who appreciate ease of entry when the truck is down.
-- We carry cargo now and again and I appreciate a lower truck when I am lifting something heavy in or out.
-- Back to towing: I am spoiled in that I can save time cranking the trailers up and down to ball level by raising and lowering the truck instead.
-- We hate washboard...and AHC almost eliminates it!
-- I do my own preventive maintenance and don't mind flushing the AHC according to the Toyota schedule.
-- We don't drive high-speed off road.
-- We don't purposefully leave the ground(!)
-- We don't rock crawl
-- I may get the itch once or twice a year, but I probably won't ever put sliders on my 570
-- *** The fact that I can't put Slee bumpers front and back and still maintain my stock cargo and towing capacity doesn't bother me a whole lot...just a little. Well, more than a little, but I've traded away that requirement and can live with it.
-- If it ever does fail, the chances are exceedingly low that I will be somewhere very far off road.

Bottom Line: For my requirements, AHC is perfect and Toyota's execution has been perfectly reliable and effective on both my '00 LX 470 and '11 LX 570.

This is a really great long-term use case and data point. Could you please share the “maintenance schedule” you’re referring to (I might have missed it in the owner’s manual — many folks mention 60K, but I’m curious if others do it more often, and if so, why?). Also, if you have time, could you share your personal to-do list for doing a 200-series fluid flush?

There are a few videos on YouTube that show the flush in a 200-series ( ), but I wanted to gather more info on this prior to attempting this myself.

Next bit of advice for prospective LX buyers during a pre-buy inspection: the fluid reservoir is behind the rear passenger tire (there’s a toaster-sized space tucked behind an access panel in the wheel well). With dirt/dust gathering on the white plastic reservoir chamber, it’s difficult to see the level, whether in the day or night. So I recommend a strong flashlight and potentially a telescoping mirror. The flashlight is hard to position behind the reservoir, so shining light straight at it and using mirror might work. What you’re looking for is a value in the mid-range, as with other fluids.

More experienced AHC users, some question — (1) what color fluid shluld we expect to see during a pre-purchase inspection; (2) are there viscosity changes with the fluid that we should be aware of resulting from time, repeat heat transfer, etc.; (3) other things that you’ve observed in the old fluid when flushing the AHC that you want us to be aware of?

The Owner’s Manual mentions that the AHC will not work below -30 Celsius weather. Alaskans/Canadians/Patagonians/Tundrans — have you observed that limitation in real-use cases at those temp ranges?

Have Arctic AHC folks run antifreeze as AHC fluid? What is chemical make-up of AHC fluid? If you’re a newbie looking for info on sourcing the fluid, here is a separate ih8mud thread on that (
AHC fluid out of stock nationally, any ideas where else to get?). Fluid itself seems same for 100-series AHC and 200-series AHC, and there is/was apparently some confusion about part number for the AHC fluid. The main warning there is to use OEM Toyota fluid — unless other folks run other fluids successfully and want to share. Also, do NOT use brake fluid, as it eats away at the membranes in accumulator globes. Lastly, if getting this serviced by mechanics — including Toyota/Lexus techs, the received wisdom on all the forums seems to be to double and triple check that they will be indeed flushing with AHC fluid and not some other fluid. Apparently several instances of dealer service departments making bad flushes with brake and/or other fluids.

Also, here are links to other VERY HELPFUL step-by-Stein threads with AHC fluid change tutorials —
AHC Fluid Change How To -- Need Input

 

[longranger]

Great post. Love the pics of the AHC components. It looks like space ship stuff compared to even the most sophisticated aftermarket suspensions.

I fondly remember this post back in the, I'll call it "before AHC" times.

Thank you — my favorite photo of the three is the second, with the faint outlines of the LX in the L/N/H mode right behind the truck. It’s not very noticeable at first blush, but that’s what those graphics are.

Also, it should be borne in mind that the AHC also raises the entire rig an inch or so even higher than H mode in particular “recovery” situations, such as when you’re in L4 and/or the diffs are locked. I haven’t learned more about this yet, except for my one encounter being stuck in some hard core mud in the LX, and I was in H/L4/Crawl when I got stuck, and I distinctly remember the truck AHC lifting even higher. If that extra 1” allows folks to get additional bumper clearance of slide in/access more traditional recovery gear, then so much the better.

 

[FinallyGotOne!]

 

[FinallyGotOne!]

I have yet to need to change fluid in my 570. The old fluid in my 470 would always be a bit brownish/yellowish (think old brake fluid) and the new fluid would be clear. I would vacuum most of the old fluid out of the reservoir, fill with the new fluid, and start bleeding at the farthest corner. When the new fluid arrived, it was very noticeable due to the color change.

I always bought fluid from the Toyota dealer and they always had it in stock.

 

[Noah Miller]

Does someone have good pictures of the reservoir behind the rear wheel along with the door to access?

I'm planning to accomplish this over a weekend, and thought my reservoir was under the hood. I had a plan for extraction of old fluid before refilling, that I may need to change and get another suction device.

 

[coleAK]

I’m in Alaska, as for the extreme cold. I have a 2013 LX and the last 4 or 5 winters have been mild (by our standards). The coldest I remember was -28 in my way to work and that was this past January. I remembered the -30 thing so I lowered it and raised it back up with no warning lights or drama.

 

[Chocolate]

View attachment 1678562


View attachment 1678564


View attachment 1678565

Can you post the full procedure?

 

[Chocolate]

I have yet to need to change fluid in my 570. The old fluid in my 470 would always be a bit brownish/yellowish (think old brake fluid) and the new fluid would be clear. I would vacuum most of the old fluid out of the reservoir, fill with the new fluid, and start bleeding at the farthest corner. When the new fluid arrived, it was very noticeable due to the color change.

I always bought fluid from the Toyota dealer and they always had it in stock.

In this respect a better design. I am doing the same thing with my power steering fluid (replace with ATF WS) and will post results soon.

 

[longranger]

Does someone have good pictures of the reservoir behind the rear wheel along with the door to access?

I'm planning to accomplish this over a weekend, and thought my reservoir was under the hood. I had a plan for extraction of old fluid before refilling, that I may need to change and get another suction device.

Here are some photos fthat me

 

[Noah Miller]

Thank you very much. The filler is the white twist cap with the hose in it right? I'm going to need a longer suction hose for sure.