What happens when the AHC fails on an LX470?

[jltemlock]

Hi All:

I'm thinking about graduating from my 1993 80 series to a stock (for now) 2001 LX470 with 240K miles on it. It still has the AHC and I know those systems can be finicky. I'm curious if it is catastrophic to drivability when the AHC goes? I'm thinking about keeping the AHC as long as it's good and will kick the can down the road on redoing the suspension and a proper lift until I have to. With that said, I don't want to get stuck on an adventure in the middle of nowhere or cruising down the highway at 70MPH if it renders the truck undrivable in the worst cases.

Thanks in advance for the guidance. Looking forward to hearing everyone's perspectives, including why I should or shouldn't trade up from my 80

 

[TexLexican]

it sounds like rusty ahc lines are the sure way to take down the system and when it goes it’ll drop to low.

My ‘99’s ahc system was ignored (besides maybe one half ass fluid change) until 20 years later and it still performed. The ride wasn’t great but it could still cycle through all the height settings. It’s a robust system where even if everything is shot or ignored it shouldn’t leave you stranded.

I haven’t heard of anyone’s ahc pump going out either.

 

[excessive]

If the ahc fails, the truck is “pretty much”undrivable.

 

[chuckscap]

If the ahc fails, the truck is “pretty much”undrivable.

Disagree. Mine failed on my 2000 LX470 so it went to low. Drove fine but too low to go offroad I had Slee replace it with an OME Medium 1.5" lift suspension., luckily my used car warranty paid for it. They lost money on me!

 

[GTV]

If the system is maintained (regular fluid flushes and pressure corrections) the only thing you really need to be concerned about failing is the height sensors. I keep extras in my rig just in case.

If the ahc fails, the truck is “pretty much”undrivable.

Kinda depends. Bad sensors caused my nose to be in the air from southern Michigan to Minneapolis. Ride quality was horrific and it wasted the front tires but I made it. If one end goes in the dirt you’re going to have a real bad time.

 

[jLB]

I'm thinking about graduating from my 1993 80 series to a stock (for now) 2001 LX470 with 240K miles on it. It still has the AHC and I know those systems can be finicky. I'm curious if it is catastrophic to drivability when the AHC goes? I'm thinking about keeping the AHC as long as it's good and will kick the can down the road on redoing the suspension and a proper lift until I have to. With that said, I don't want to get stuck on an adventure in the middle of nowhere or cruising down the highway at 70MPH if it renders the truck undrivable in the worst cases.

I transitioned from an 80-series, to a 100-series, about 21 years ago. If we’re only talking about (slow) off-road ability, the 80-series is clearly superior. If you have to drive ~1500 miles, on the highway, to go play off-road, or spend most of your time on-road, the 100-series is clearly superior.

It would depend on what’s broken. Failed globes would cause a “bouncy ride”, annoying but not catastrophic. A blown line, typically due to rust, could put you on the bump stops, nearly undrivable. Bad height sensor, maybe OK, maybe not, and so on…

My ‘99’s ahc system was ignored (besides maybe one half ass fluid change) until 20 years later and it still performed. The ride wasn’t great but it could still cycle through all the height settings. It’s a robust system where even if everything is shot or ignored it shouldn’t leave you stranded.

Again, it would depend on exactly what is broken. Bad/worn globes behavior, or out of spec pressures are not the same as a blown hydraulic line.

Just because it moves to L-M-H, doesn’t mean that it is fully functional.

I haven’t heard of anyone’s ahc pump going out either.

It’s based on an electric motor, which will eventually fail, although most failures that I’ve seen, has been due to trying to work around contaminated fluid (from a plastic bottle), while trying to service the system.

The pumps out of my 06 LX, and 99 LX, were “gifted, to help locals, with a broken pump.

If the ahc fails, the truck is “pretty much”undrivable.

Again, depends on what fails.

Disagree. Mine failed on my 2000 LX470 so it went to low. Drove fine but too low to go offroad I had Slee replace it with an OME Medium 1.5" lift suspension., luckily my used car warranty paid for it. They lost money on me!

Again depends on what fails.

If the system is maintained (regular fluid flushes and pressure corrections) the only thing you really need to be concerned about failing is the height sensors. I keep extras in my rig just in case.

Or depending on where the truck lives, rusty hydraulic lines. Don’t I remember a few around here with a burnt harness, due to an exhaust leak as well?

The AHC system is fairly robust, and in stock form, on a stock vehicle, within factory specifications, it does ride very well, for a nearly 6000lb vehicle.

Once you’re well above GVWR, and replacing springs/bars with non-AHC components, operating well outside the original Toyota design, I’m not so sure I believe the “magic”

If you have the physical ability, technical ability, and desire, to maintain it yourself, by following @suprarx7nut ’s guide(s) it might be worth keeping.

If you’re relying on someone else to maintain it for a fee, you’ll likely find that nobody wants to, and/or they want to use the “parts cannon” method of diagnosis, with ridiculous prices.

 

[rexington14]

Ever seen a Mercedes E or S class with a blown AirMatic suspension? The body literally sits on top of the tire(s). The car isn't driving anywhere. Pretty common sight on city streets.

 

[Exiled]

You'll find a passionate contingent here that swears by a baselined, well-maintained AHC and may of these rigs are used regularly offroad without issues. In my opinion, the ride on a properly functioning AHC is hard to beat on these big beasts, and it's much better than the one with an off-the-shelf suspension kit.

You'll also find a contingent of folks that either had a strong preference for conventional suspensions, or couldn't /wouldn't deal with repairs and maintenance and thus opted to replace the AHC with a conventional suspension kit. It's rare here for people to just replace a fully operational AHC setup, but some folks have.

Neither one of my current 100s came with the AHC but I was also born and raised in the Third World, which gave me a healthy but completely irrational aversion to additional complexity in Land Cruisers if I can avoid it. Not justifiable with logic but it's there and I don't fight it anymore. It's the same reason why I still prefer steel wheels above alloy, even though forged alloy wheels are lighter and stronger (and in many cases prettier) than my trusty old steelies.

 

[NeedaLX]

On the topic of AHC lines and rust - what is the best way to protect them? Any issue or difficulty with fluid filming?

 

[Rhetoric]

On the topic of AHC lines and rust - what is the best way to protect them? Any issue or difficulty with fluid filming?

Coat everything with your rust prevention of choice. I do RP342 every fall before winter sets in. Zero issue with it. The difficulty can be getting to every single nook and cranny, but if you take your time you can do it.

 

[NeedaLX]

Coat everything with your rust prevention of choice. I do RP342 every fall before winter sets in. Zero issue with it. The difficulty can be getting to every single nook and cranny, but if you take your time you can do it.

Thanks A thorough coating is the plan before my LX and AHC sees its first winter

Just haven't been under the vehicle much yet to see how everything is routed. Those lines will definitely be an area of emphasis

 

[kevgentile]

You'll find a passionate contingent here that swears by a baselined, well-maintained AHC and may of these rigs are used regularly offroad without issues. In my opinion, the ride on a properly functioning AHC is hard to beat on these big beasts, and it's much better than the one with an off-the-shelf suspension kit.

You'll also find a contingent of folks that either had a strong preference for conventional suspensions, or couldn't /wouldn't deal with repairs and maintenance and thus opted to replace the AHC with a conventional suspension kit. It's rare here for people to just replace a fully operational AHC setup, but some folks have.

Neither one of my current 100s came with the AHC but I was also born and raised in the Third World, which gave me a healthy but completely irrational aversion to additional complexity in Land Cruisers if I can avoid it. Not justifiable with logic but it's there and I don't fight it anymore. It's the same reason why I still prefer steel wheels above alloy, even though forged alloy wheels are lighter and stronger (and in many cases prettier) than my trusty old steelies.

I'm one of those rare cases. I have a healthy AHC system that'll be getting replaced with Dobinsons triples.

I'm pro-AHC and love the system and does very well offroad. However, I live out of my LX full-time. Between that and offroad use with 35's, and soon 37's, it just makes since to have something more "bullet-proof".

My logic parallels yours, the simpler the better. I've already sorta turned the LX into a "poverty edition".

 

[Kabanstva]

If the system is maintained (regular fluid flushes and pressure corrections) the only thing you really need to be concerned about failing is the height sensors. I keep extras in my rig just in case.



Kinda depends. Bad sensors caused my nose to be in the air from southern Michigan to Minneapolis. Ride quality was horrific and it wasted the front tires but I made it. If one end goes in the dirt you’re going to have a real bad time.

Yeah it went on low for us several times on the trail. That’s when I decided ahc had to go. Low miles too barely over 100k

 

[Import Driver]

This is a very interesting thread, at least I'm very interested in it. I agree with many of the comments.
I lived in a developing country for over 10 years. I owned a 70 series Land Cruiser and a 2nd gen Tacoma which both seemed simple compared to my LX. Now back in the US, I often worry about my AHC. While it rides nice, I assume the lines will rust out at any moment. While I have the basic understanding of the system and have the ability to make sure all of it is in tip top shape, in reality AHC suspension is the last thing I want my time and brain power being dedicated to, and that's what it comes down to for me to period. I hate worrying about it and for that reason I would just prefer to have conventional suspension. I sure would like to ride in a 100 with conventional suspension to get a chance to experience it.

On a side note, if (or when) one of my AHC lines does rust through, I think I'm going to try using OEM shocks with AHC front torsion bars and AHC rear springs with airbags. That should be an interesting experiment since I have an Ironman front bumper.

 

[BullElk]

I guess I have AHC experience across a sizable spectrum.

Bought a mint ‘04 LX with 317k very cheap with shot AHC globes. Replaced with Plaeides globes increasing total cost in the LX to $5800ish. Been wife’s daily driver for 6-7 years now. No other AHC components replaced.

Son drives a 2000 LX that had globes go out in normal fashion at about 275k miles. Replaced with good used globes bought here from a kind mudder. Now has the normal buttery ride. No other AHC components replaced.

My 2001 LX, globes slowly began showing a little bounce around 250k miles. After a speed bump diagnois one wheel at a time, I decided to replace three globes, sort of experimentally, with cheap Amazon globes. Rides great for a few months now at least. No other AHC components replaced.

My daily driver 2000 LX with all original AHC components until 462k miles. Finally decided to replace with used globes from my '06 LX below. Rides ok but will be replacing a couple or all fairly soon. No other AHC components replaced.

On the other, rarest end of the spectrum is my '06 LX overlander. Bought it with 212k miles with needing rear globes. Replaced with Plaeides globes and rode great for years. I don't remember mileage at the time but began having issues with rear end not holding up when loaded. After much appreciated assistance and patience from other mudders here, taking AHC pumps and motors apart, cleaning pumps, troubleshooting to no end i finally replaced O rings in pump and AHC came to life.

Then on one of our truck camping trips, the rear end sank again. As much as I love and recommend AHC, that eight hour bumpstop ride home scarred me for life. I immediately replaced it with LC torsion bars, OE shocks and OME springs and Airlift 1000 bags in rear.

So if not depending on your LX for successful overlanding, there are too many good smooth riding, lowering and raising reasons to keep the factory AHC.

 

[GTV]

I think I'm going to try using OEM shocks with AHC front torsion bars and AHC rear springs with airbags. That should be an interesting experiment since I have an Ironman front bumper.

Interesting? I think we all know how that’s going to work out.

 

[kevgentile]

I'm 300k on a completely original AHC system. As a professional mechanic, I will say the Toyota AHC is by far the most capable, reliable, and damn near bulletproof dynamic/adjustable suspension ever produced. If ever there is a system fault, it is usually corrected with very simple repairs.

It's only after turning mine into a full-time dwelling/overlander/offroad unit, that I am now making the switch to a conventional system.
I have developed some weird behavior in my AHC that while solvable, can potentially lead to timely diagnostics and a bit of trial and error.

Additionally, the one area that bothers me the most and really not correctable, is the terrible high speed compression/bump dampening.
I can tolerate some quirks here and there, but this is one area that is irritating me more and more with each passing day. I have confidence
that the Dobinsons triple adjustable's will go a long way in dialing this out.

 

[David310]

I would baseline your AHC and pick up extra height sensors (2 in the front and 1 in the rear) until you're ready/need to make the shift for peace of mind. You should be able to resell the spare sensors close to purchase price.

 

[suprarx7nut]

Ever seen a Mercedes E or S class with a blown AirMatic suspension? The body literally sits on top of the tire(s). The car isn't driving anywhere. Pretty common sight on city streets.

Difference being that those Mercedes systems are 100% air, so there's no mechanical assist when the air bags fail. The LX isn't quite as bad.

On the topic of AHC lines and rust - what is the best way to protect them? Any issue or difficulty with fluid filming?

Not living (or purchasing a car that ever spent time) anywhere east of the Mississippi.

If you're in the east where it's humid and they salt the roads you're pretty well toast. I'm sure fluid film and the like help, but you're still going to have areas that the salty moisture hang out and eat the lines over time.

On a side note, if (or when) one of my AHC lines does rust through, I think I'm going to try using OEM shocks with AHC front torsion bars and AHC rear springs with airbags. That should be an interesting experiment since I have an Ironman front bumper.

Your experiment there is basically what the Strut masters kit attempts to do. And it's arguably unsafe. Certainly not acceptable, IMO. I'm surprised they haven't been sued for offering such a poor product.

The physics dictate you need different front springs without AHC. Can't get around that. The rate with and without AHC is very, very different.

 

[uHu]

IF you are planning on being in "the wild open" frequently, it is probably more reliable with a conventional suspension. The standard LC100 suspension is superb, giving a very good ride for the cost. It doesn't give you any lift, but that is perfectly ok for most overlanding/expedition style adventures.

.... I think I'm going to try using OEM shocks with AHC front torsion bars and AHC rear springs with airbags. That should be an interesting experiment since I have an Ironman front bumper.

"Interesting" is not the right word. That is a word which may have a positive connotation, which is completely wrong in this case.