Props to PADDO's AHC fluid replacement method! (12 Viewers)
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Sweet. Let that pump run again and see what you get. If it's any higher or a higher pressure you're making progress. If you're seeing bubbles you've either got a dying globe or just air still trapped from a failed flush/bleed. Keep bleeding that left side!
I got no bubbles from the left side when I went back but the values did change slightly from the last time. but it's still maintaining N which is good. I'm afraid to test N to H lol. I was able to go from N back to L and then back to N again though.
Awesome. As with brakes or a clutch, any little bubbles are failure inducing. It takes very little.
Go for h!
lol I tried 3 times and all 3 failed. I got a code C1762 on the first attempt and then a code C1751 on the last 2 attempts. On the first attempt, I wasn't getting any pressure at all to the front. and the second attempt failed right when the front started to build pressure. Here are the values in order of attempts.
You've got less gas, but you still have gas. Bleed and watch very carefully for bubbles. And keep that reservoir full.
Now I see why people give up on this system. This can get really frustrating. Spent 3 hours bleeding and finally got it to H. Went back to N then to L and then I couldn't get back to N again. During those 3 hours, I had times when the fluid was coming out nice and clear with no bubbles. Then out of nowhere, I get a whole bunch of them and at one point, the fluid came out all frothy. Ended it for today when I was able to get it back up to H for the second time. Fluid came out clear during bleeding. I lowered it back to N and the fluid came out clear again. I'm leaving it at that and I'm going to tackle it another day. Here are the last values I got when I went from H - N - L.You've got less gas, but you still have gas. Bleed and watch very carefully for bubbles. And keep that reservoir full.
Frothy AHC fluid generally means you have a dying globe releasing nitrogen gas. This would also explain your bleeding difficulty where the air just keeps coming.
If I can offer some advice beyond the scope of this tedious bleeding exercise:
1. You're good on bleeding for now. Leave it be.
2. Buy a set of globes. They are not meant to last longer than ~10 years and new globes can make a huge improvement in ride quality. They are just like shocks on a normal car. Shocks wear out. The AHC shocks don't wear out, but the globes do (because with AHC the globes are the "shock"). Replace them. ~$650 from Impex. IMPEX JAPAN — online new genuine spare parts shop - https://en.impex-jp.com/
3. If you need to bleed more and the first round or two doesn't do it in the future, use the method where you override the pump to force it to just run. A teammate helps with this. You trigger the pump to run *while* a bleed port is open. You can bleed a lot in a short period of time this way. It's normally not needed, but in the odd cases where you just can't get all the bubbles out, it works more quickly.
ramangain
Clarksonian disciple
Since your accumulator pressure is still low, you may have accidentally introduced a $hit ton of air in the system via the accumulator (you are not unique, I did this too back in the day). No worries, over and done with; you're on the right track to chase out the air. I'd keep bleeding the accumulator, adjust the torsion bars, then do a graduation test.
If you REALLY wanna speed up the bleeding, keep the rig running while opening and closing valves. Keep the reservoir fully topped, and recycle bled fluid if it looks good.
I am a new and first time LX owner. I want to keep and maintain the AHC system, so I have been doing some forum reading over the past few months. I have ordered AHC fluid, and I have a functional techstream. Side note, I ordered this one (Amazon product ASIN B088RJSR5Y) and the software installed right up on Windows 10 64bit with no problems and no need for virtual box. I already checked my AHC info on techstream and my pressures/heights are definitely out of whack. There was no available history of the AHC system ever being serviced, so I am going to assume everything is 146k miles original, including fluid. I did the grad test when I test drove it, and it was right around 7-8. I am going to flush and replace the fluid, and I am going to work on getting the pressures/heights back in line.
My question is should I replace the fluid first and then work on the pressures/heights? Or should I start on the pressure/heights to get them more in line, change the fluid, and then readjust the pressure/heights as needed again? I'm sure I will replace the globes at some point to get the best out of my system, but I want to start here before forking that money over.
Low: FR -49.4mm, FL -49.8mm, -39.4mm, Front 0 MPa, Rear 0 MPa
Neutral: FR -0.6mm, FL -2.4mm, RR -1.4mm, Front 8.0 MPa, Rear 6.9 MPa
High: FR 40.6mm, FL 36.8mm, RR 49.6mm, Front 10.9 MPa, Rear 3.9 MPa
Techstream seemed to default to mm instead of inches. I didn't search very hard to find how to change it.
My question is should I replace the fluid first and then work on the pressures/heights? Or should I start on the pressure/heights to get them more in line, change the fluid, and then readjust the pressure/heights as needed again? I'm sure I will replace the globes at some point to get the best out of my system, but I want to start here before forking that money over.
Low: FR -49.4mm, FL -49.8mm, -39.4mm, Front 0 MPa, Rear 0 MPa
Neutral: FR -0.6mm, FL -2.4mm, RR -1.4mm, Front 8.0 MPa, Rear 6.9 MPa
High: FR 40.6mm, FL 36.8mm, RR 49.6mm, Front 10.9 MPa, Rear 3.9 MPa
Techstream seemed to default to mm instead of inches. I didn't search very hard to find how to change it.
The Techstream numbers at "N" height are the Techstream numbers which matter and are the reference points when setting up or adjusting your AHC system. The other important numbers include the actual physical tape-measured heights of the vehicle when "N" height is selected, usually measured by tape-measure from hub centre to the fender lip above -- for a stock vehicle: Front 19.75 inches or 500 millimetres, Rear 20.5 inches or 520 millimetres, independent of wheel/tyre size. (These physical height numbers do not come from the Factory Service Manual but are the widely used, easier-to-measure approximations of the more precise height specifications for a stock vehicle as set out in the FSM).
Physical heights are important -- if the vehicle is higher than the above numbers at "N" setting, then the springs/torsion bars are carrying a reduced share of the vehicle weight and AHC system is carrying an increased share. The consequence is increased AHC pressures.
If your vehicle is at or near the above-mentioned physical height numbers, then your quoted AHC pressures -- Front 8.0 MPa, Rear 6.9 MPa -- are higher than FSM specifications for AHC Front and Rear pressures. The FSM pressure specifications relate to correct physical tape-measured heights at "N" height setting.
A good start would be to wind equally both Front torsion bar adjusters clockwise (when looking up from below the adjuster bolt) 4 or 5 turns (at about 0.2 MPa change per turn on both adjusters), then re-check pressures and fine-tune this adjustment. Rear pressures are harder to fix -- usually require at least spacers and more likely new coil spring. It is best to start at the Front.
Your Height Control Sensor readings at "N" height on Techstream are reasonable at FR -0.6mm, FL -2.4mm, RR -1.4mm. They are meant to be close to zero and are the point to which the AHC system self-adjusts the vehicle height when the AHC system is operating. The difference between FR and FL may indicate that vehicle is not quite cross-level at the Front. This should be checked with a tape-measure per attachment below and if necessary adjusted using the torsion bar adjusters. If the vehicle is cross-level at the Front (within the given tolerance), then the quoted different Front Height Control Sensor readings may suggest that these Sensors are slightly out of adjustment -- but frankly not enough to worry about unless there are other symptoms or concerns.
The HI/LO difference-in-numbers-of-graduations test, quoted as around 7-8, is indicative only -- to be comparable with FSM specifications this test must be done with the Front and Rear AHC pressures in the correct range.
Seems like your vehicle is '06/'07 and only 146,000 miles and is very good condition. Even so, it is more than likely that the 'globes' are past their best and replacement is in your inevitable future, at around USD700 for a set of two Front and two Rear delivered to you from IMPEX JAPAN — online new genuine spare parts shop - https://en.impex-jp.com/. Also search "Impex" in this Forum. When installed, new 'globes' then should be good for another 10 years or thereabouts.
The USA Owner's Manual suggest AHC Fluid change every 6 years or 60,000 miles -- but frankly changing this fluid more like every 3 years or 30,000 miles is a better, more conservative idea for long life of AHC components.
Many Owners report improvement in ride quality after replacement of ancient AHC fluid.
Definitely yes -- replace AHC Fluid now if you are not ready to replace 'globes' but read the threads on fluid replacement and focus on not allowing air into the system.
If replacement of 'globes' is in the very near future, you might wait until then to replace the AHC Fluid, as the AHC system must be bled as part of the task of replacing 'globes'.
If you have not seen them, this list of references is helpful in understanding the AHC/TEMS systems -- suggest start with the "AHC/TEMS General Description" further down in this list which gives good explanations and diagrams:
A basic IH8MUD reference on AHC matters:
The ABCs of AHC - How to Measure, Flush, and Adjust all in one place - https://forum.ih8mud.com/threads/the-abcs-of-ahc-how-to-measure-flush-and-adjust-all-in-one-place.1211999/
As you know, there are many other detailed threads on IH8MUD in which AHC/TEMS questions and answers are discussed.
Video:
AHC Info - https://www.yotamd.com/blogs/news/ahc-info -- this provides great information and visuals.
Yotamd contributes extensively to IH8MUD under the Member Name @suprarx7nut
Factory Service Manual (FSM) references relevant to AHC/TEMS:
The AHC/TEMS General Description by Toyota/Lexus with good diagrams setting out how the AHC and TEMS systems are supposed to work is found in the Factory Service Manual (FSM). It is an informative and easy read:
Go to: https://lc100e.github.io/manual/
(This is a Toyota LC100 manual but under the skin where most things are the same, especially for AHC/TEMS, it does just as well for LX470):
At the tabs at the top on the left hand side of the opening page at the above link, go to:
New Car Features > CHASSIS > Suspension > Active Height Control and Skyhook TEMS
Eventually you will need to know something about AHC specifications, settings and and inspections:
Go to: https://lc100e.github.io/manual/
At the tabs on the left hand side of the opening page go to:
Repair Manual > SUSPENSION AND AXLE > ACTIVE HEIGHT CONTROL SYSTEM (Independent Front Suspension)
then look at the tabs for BLEEDING, ON-VEHICLE INSPECTION, LOCATION, ADJUSTMENT
As you become more familiar with the vehicle, the section on AHC/TEMS Diagnostics reveals many deep secrets!
Go to: https://lc100e.github.io/manual/
At the tabs on the left hand side of the opening page go to:
Repair Manual > DIAGNOSTICS > ACTIVE HEIGHT CONTROL & SKYHOOK TEMS
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In the description by @PADDO at Post #4 in this thread, "PS" at Step 9 means "Passenger Side".
Yes -- the process is "simple" but take care. If air enters the system while bleeding, many patient repetitions of the process and some variations can be required to get it out.
This is a long thread -- the many experiences reported here by others contain wisdom worth reading if not already seen.
The attached extract from the Factory Service Manual (FSM) summarises the basic idea for bleeding the AHC system but does not give much detail.
This FSM extract also refers to the "Active Test" if needed to re-start the AHC Pump -- which may be necessary if air enters the pump. The "Active Test" can be done via Techstream, or, it can be done manually using the information on the second attachment (source: @PADDO) -- at Page 6, see item 5 "Height Control Operation Test - Active Test. (The reference to Special Service Tool SST 09843-18020 is a reference to simple bridging wire -- experience shows that an unbent paper-clip is just as good!)
The references given at the end of Post#251 in this thread also may be helpful.
The many posts by @suprarx7nut in various IH8MUD threads always provide helpful insights. His video is a good starting point, see -- AHC Info - https://www.yotamd.com/blogs/news/ahc-info
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Thank you @IndroCruise @suprarx7nut and of course @PADDO for taking the time to give detailed and helpful replies, so much patience you guys have and a wealth of knowledge to share - what a terrific resource this forum is.
@IndroCruise - took your advice and carefully read through each of these 13 pages, glad I did. Sounds like air in the system is hell. Understand the need to be careful. One thing I'm still unclear on.... what are the particular steps I need to do (or not do) to avoid getting air in the system?
I'm planning to use @suprarx7nut's cheat sheet from his video to first measure heights, adjust pressures, and only then do the fluid exchange per @PADDO instructions.
I have a 2006 SoCal LX with 185K on the odo, no rust, graduations at around 7-8, measured pressures as below, but later realized I wasn't on super flat ground. Also I haven't taken height measures first, which sounds like a pre-req.
@IndroCruise - took your advice and carefully read through each of these 13 pages, glad I did. Sounds like air in the system is hell. Understand the need to be careful. One thing I'm still unclear on.... what are the particular steps I need to do (or not do) to avoid getting air in the system?
I'm planning to use @suprarx7nut's cheat sheet from his video to first measure heights, adjust pressures, and only then do the fluid exchange per @PADDO instructions.
I have a 2006 SoCal LX with 185K on the odo, no rust, graduations at around 7-8, measured pressures as below, but later realized I wasn't on super flat ground. Also I haven't taken height measures first, which sounds like a pre-req.
We’ve run across several bad bottles of AHC fluid in the 200 forum. There is a gel in the bottle and it is immediately clogging the pump and filters before the pump.
Please treat any recently purchased 1L bottles as suspect.
I think I read somewhere on the 100 forum about filtering the fluid that came installed in new shocks- I’d like to find out what the filter media/ process is so we can start remediating bad fluid. Does anyone have that post favorited?
Have any of you found a non OEM source for an alternate AHC fluid?
Please treat any recently purchased 1L bottles as suspect.
I think I read somewhere on the 100 forum about filtering the fluid that came installed in new shocks- I’d like to find out what the filter media/ process is so we can start remediating bad fluid. Does anyone have that post favorited?
Have any of you found a non OEM source for an alternate AHC fluid?
In my part of the world (Australia), AHC Fluid comes from directly from Japan in 2.5 litre drums and so I cannot comment on the 1 litre plastic bottles which seems to be the packaging of choice in USA. I have never had problems with new AHC Fluid which I have purchased in the 2.5 litre drum format as recently as last month.
Given the suspicions, if I were the recipient of the 1 litre plastic bottles of AHC Fluid, I would be inclined to tip the contents into a clear glass or clear plastic container so that I could inspect it before use. The new AHC Fluid should be a light pink (rose) colour. Gel or sludge or other problems should be visible, even if only because any gel would be of a different density and would be quite obvious when held up to a light. Faulty fluid should be discarded -- or better still, put back in the original container and returned to the manufacturer (Idemitsu) for testing.
AHC Fluid is manufactured or blended exclusively for Toyota/Lexus by large Japanese oil company Idemitsu Kosan Co., Ltd which also has operations in USA.
As best I understand, the different Toyota/Lexus part numbers relate to different packaging of the same fluid for different markets.
Toyota/Lexus Part No. 08886-01805: This is a 2.5 litre steel drum of genuine Toyota/Lexus AHC Fluid. It is the longstanding and current format available in Australia and in Asia and possibly elsewhere.
Toyota/Lexus Part No. 08886-81221: This is a 1 litre (1 quart?) plastic bottle of genuine AHC Fluid which seems to be the common format distributed in USA.
The source of the fluid is printed on my steel drums -- Idemitsu Kosan Co., Ltd.
I can see website pictures of the labelling on the plastic bottles -- these show the same maker and source of fluid -- -- Idemitsu Kosan Co., Ltd.
I am not aware that there is any difference in the actual Fluids.
Years ago, I worked for a Joint Venture in which Idemitsu was involved -- the company was known for its customer focus and quality.
You may wish to call or e-mail Idemitsu in USA -- contact details are within the links below. They should be able to provide some advice. They would be concerned if there are fake or defective or recycled products in circulation.
The Trusted Choice of Leading Automakers Worldwide | Idemitsu Lubricants
The trusted choice of leading automakers worldwide for lubricant solutions.www.idemitsulubricants.com
Idemitsu Lubricants America | The Perfect Blend of Service, Technology and Innovation
Idemitsu Lubricants America Corporation is a manufacturer of finished lubricants for a variety of applications including the automotive and industrial markets.www.ilacorp.com
Idemitsu Lubricants America | Contact Form
I have seen mention of an alternative European suspension fluid made in Germany which is labelled as suitable for Toyota and Lexus suspension systems:
RAVENOL AHC Active Height Control Fluid | RAVENOL - https://www.ravenol.de/en/product/hydraulikoel/pkw-hydraulikoel/ravenol-ahc-active-height-control-fluid
It may be good stuff but I have not seen reports of its use on any Toyota or Lexus forum. I would not be inclined to use it unless I had seen a clear written endorsement from Toyota/Lexus. Maybe some European IH8MUD Members can comment??
Meanwhile, I will stay with the known Toyota/Lexus-branded AHC Fluid made by Idemitsu.
Other common fluids -- such as brake fluid, auto transmission fluid, power steering fluid, etc -- should be strenuously avoided and very clear instructions given to unknowledgeable service people that these fluids NOT be used in the AHC system. The composition of many of these fluids cause degradation of 'globe' membranes and other parts. The debris formed certainly will cause blockages in the AHC Pump internal filters as well as blockages in valve arrangements throughout the AHC systems in LX470, LX570 and LC100 (where fitted).
".... read somewhere on the 100 forum about filtering fluid that came installed in new AHC shocks"?? -- never heard nor seen AHC shocks which are sold pre-filled. Hard to understand this idea as LC100/LX470 'shocks' are little more than hydraulic struts which are transported and sold empty of fluid. The usual recommendation is to operate the 'shocks' like a syringe to draw fluid into them immediately before fitting. The aim is to reduce the amount of air which otherwise would be introduced into the AHC hydraulic circuit by an empty 'shock' and which then would have to be bled out.
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Yeah, I have this fuzzy recollection on the shocks. It was several years ago, and the pics had kind of a pink, cloudy look. Definitely there was filtering going on, but it could have been during a shock replacement on the previous shock fluid.
Yes, people are pouring out the plastic liters into a clear container to assess, but so far most Toyota/Lexus dealers are disallowing knowledge of a supply chain issue, and in general not providing a solid response to returns and issues. A few have worked with buyers on new pumps etc, but it certainly hasn't been a coordinated response from Toyota.
Yes, people are pouring out the plastic liters into a clear container to assess, but so far most Toyota/Lexus dealers are disallowing knowledge of a supply chain issue, and in general not providing a solid response to returns and issues. A few have worked with buyers on new pumps etc, but it certainly hasn't been a coordinated response from Toyota.
I tried to get some more info a few weeks ago, but I couldn't find much. I bought 3 of the plastic liters online from a dealership, and then I picked up 1 more from a local dealership. The local dealership said they only had 2 because of a nationwide recall. I called the dealership that I bought 3 from, and they didn't know anything about a recall.... I will pour all of them into clear containers before I use them. Hopefully they all check out.
I just ordered 3 L from Mcgeorge Toyota to fluid exchange my AHC system and it was completely fine, no gelling at all. However, Mcgeorge is only selling 2.5 L canisters now... No more 1 L bottles. Still, you can get 2.5L for $38 which is a pretty solid deal.
Anyone have any idea why my rear pressures may still be high (7.2 mPa) after brand new AHC springs were installed? Front is levelled, and roughly in-spec at 6.3 mPa. Could additional AHC components in the rear be worn out causing higher pressure on the system? or possibly a bad sensor? To clarify, the old rear springs had a pressure of 7.6 mPa, so there was some improvement...
