LX470 AHC help/info

Joined
Sep 27, 2018
Messages
18
Location
Forsyth, GA
Hi All,

After 4+ years of looking for my very own LC I came across a nice LX470 and pulled the trigger.

It's a 2004 one owner (now retired CPA), GA vehicle with a long list of service at a couple LEXUS dealerships around Atlanta (223K miles) no rust, no accidents, best I can tell everything works.

I was not really planning on purchasing a vehicle with the AHC system, but I figured if they put it on this vehicle and the LC it must be world class, right? Maybe I should give it a chance before I decide to discard it.

So, what are it's strengths & weaknesses?

It goes up. It goes down. It goes in between. Can I adjust the heights of these settings?

I do like it sitting up, like in the high position.

Upon early investigation, it seems that there are other things that I may be able to do to tweak it.

I have read a little about sensors, springs, that sort of thing. Just enough to become lost and confused. Can I replace old springs and shocks?

Someone school me. PLEASE.

I do plan to still buy a LC when the right one comes along, so this one may go to one of the kids one day.

I may do a bumper, sliders, rack, wheels and tires. Not planning on doing anything off road that would risk me not making a 100 or 200 mile trip back home. Just breaking the ice with the off road thing.

Send me your knowledge!

Thanks,
Chris
 
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Joined
Jun 19, 2013
Messages
2,100
Location
Mobile, AL
 
Enjoy the benefits of the AHC and leave it be until you possibly have issues at some point. Then remember that most everything in life is cheaper to repair than replace.
 

GTV

Joined
Jan 31, 2019
Messages
499
Location
Si'ahl
AHC is fantastic when it's working but it's a complicated system with many potential points of failure. Given the age of these trucks it's not if but rather when it will fail. Normal springs and shocks are stupid simple, cheap and will never leave you stranded.
 

suprarx7nut

The YotaMD Guy
Supporting Vendor
Joined
Sep 28, 2010
Messages
2,785
Location
Colorado
 
I'm in the pro-AHC camp. It's about as complicated as the brake system. And fails about as often. If you don't worry about the brake booster failing and leaving you stranded I don't think anyone needs to worry about AHC, either. Some basic maintenance and upkeep dramatically reduces the likelihood of failure. Rust would be the major exception to my stance on AHC. If your rig is badly rusted, AHC is far more likely to have annoying/expensive failures. Rust-free rig? Psh, nothing to worry about.

The core components are not complicated and are not very expensive to rebuild/replace, despite internet lore. Fluid flushes every few years and a set of globes for $1,000 every ten years and a pair of rear springs (or spacers) every ten years is about all you need. Roughly the same schedule as normal shocks and only a small bit more complicated.

The marginal increase in maintenance cost pales in comparison to the improved ride on 99.8% of road surfaces you'll encounter. It's a night and day difference.
 
Joined
Dec 6, 2016
Messages
115
Location
Brisbane, Australia
Hi All,

After 4+ years of looking for my very own LC I came across a nice LX470 and pulled the trigger.

It's a 2004 one owner (now retired CPA), GA vehicle with a long list of service at a couple LEXUS dealerships around Atlanta (223K miles) no rust, no accidents, best I can tell everything works.

I was not really planning on purchasing a vehicle with the AHC system, but I figured if they put it on this vehicle and the LC it must be world class, right? Maybe I should give it a chance before I decide to discard it.

So, what are it's strengths & weaknesses?

It goes up. It goes down. It goes in between. Can I adjust the heights of these settings?

I do like it sitting up, like in the high position.

Upon early investigation, it seems that there are other things that I may be able to do to tweak it.

I have read a little about sensors, springs, that sort of thing. Just enough to become lost and confused. Can I replace old springs and shocks?

Someone school me. PLEASE.

I do plan to still buy a LC when the right one comes along, so this one may go to one of the kids one day.

I may do a bumper, sliders, rack, wheels and tires. Not planning on doing anything off road that would risk me not making a 100 or 200 mile trip back home. Just breaking the ice with the off road thing.

Send me your knowledge!

Thanks,
Chris

As a starter and as primer, read the AHC overview document “AHC General Description and Diagrams” so that you get a feel for the nomenclature and how the Active Height Control (AHC) and Toyota Electronic Modulated Suspension (TEMS) actually work in LC100 (where fitted) and LX470. In more recent vehicles, a successor to TEMS is called Adaptive Variable Suspension (AVS).

This document has been posted many times – and I have just now posted it again here at the bottom of a reply.

Then read all of this thread:

Definitive list of AHC maintenance items

This thread is huge unwieldy rambling thing which began in 2012 and now adds up to 811 posts. Some say it is a rite of passage which all have endured, and nobody should be allowed to escape!!!! It is also the ‘keeping place’ of a vast amount of knowledge.

Anyway, start at the beginning and you will soon get the gist of the AHC and TEMS systems and basic diagnoses – and you will quickly identify the early knowledgeable and influential contributors – PADDO, uHu and a host of others. Some of us more recent contributors simply stand on their shoulders and plagiarise relentlessly – or at least that is what I do!

To assist, @tjb helpfully created a PDF collection of this thread up to March 2019.

It is a huge PDF file but downloading is recommended because it is then easily searchable off-line and you can then make up your own list or index of the items most useful to you. This enables easy return later.

For his part, @PabloCruise nominated his favourite “pearls of wisdom” by @PADDO and collected them at this handy post.

Among the early contributors you will also come across @uHu in many different threads– always succinct, wise, to the point and always worth reading on a wide variety of matters.

More recently @LndXrsr set out to produce a concise, orderly summary "The ABCs of AHC" and this thread should be read and watched:

The ABCs of AHC - How to Measure, Flush, and Adjust all in one place

There are many, many other contributors and many, many other very informative AHC threads – I intend no offence by failing to name all those whom I have found very helpful and the threads they have produced – but the above links probably are enough material for one weekend :cheers:

It also must be said that the “Search” function on the IH8MUD Site works very, very well – and should be used a lot!

Late edit and apologies: Should have acknowledged and included the Master thread: Buying, PM & Advanced Maintenance of 100 & 200 series prepared by @2000LC .
 
Last edited:
Joined
Mar 26, 2020
Messages
57
Location
Nicaragua
Hey guys, quick question:

I am about to get new tires for my rig - 265/70R18s and I was wondering if I have to do anything to the AHC system prior to lifting the truck?

Many thanks
 

suprarx7nut

The YotaMD Guy
Supporting Vendor
Joined
Sep 28, 2010
Messages
2,785
Location
Colorado
 
Hey guys, quick question:

I am about to get new tires for my rig - 265/70R18s and I was wondering if I have to do anything to the AHC system prior to lifting the truck?

Many thanks
Press and hold the AHC off button.
 
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