Thanks again then. That was another question i had. When the initial post recommended buying two i didnt know what size. I def didn’t think the system took that much fluid. Appreciate your help.
AHC Fluid Change How To -- Need Input
- Thread starter ntsaint
- Start date
This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.
IndroCruise
SILVER Star
The first attachment is a well-regarded IH8MUD post dated April 27, 2016 by longtime contributor @PADDO describing a bleeding method and AHC Fluid requirements. This is worth printing. It is a reliable adaptation of the Factory Service Manual (FSM) method.
Many other Members have their own successful adaptations – these can be explored on the IH8MUD 100 series Forum.
When air is entrapped in the system, multiple repetitions of bleeding may be required to remove the air -- and there are IH8MUD threads in which some Members have described their experiences and frustrations and the persistence required for eventual success.
If starting out on the LX470/LC100-with-AHC journey and if not already seen, suggest have a look at
- the attached General Description of the Active Height Control (AHC) system and the real-time adaptive damping system called Toyota Electronic Modulated Suspension (TEMS) – this is worth printing,
- this thread called "The ABCs of AHC" initiated by @LndXrsr -- 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/#post-13116520 ,
- this video and a printable “cheat sheet” prepared by @suprarx7nut -- AHC Info - https://www.yotamd.com/blogs/news/ahc-info,
- information about AHC diagnostics using Techstream at this thread -- How-To: TechStream In 5 Minutes - https://forum.ih8mud.com/threads/how-to-techstream-in-5-minutes.1034923/#post-11416736,
- the Online Factory Service Manual LC100 Workshop Manual - https://lc100e.github.io/ which includes information about inspection, repair and diagnosis of the AHC/TEMS systems – common to both LX470 and LC100 (if fitted) -- suggest explore the index panel on LHS of the opening page.
Last edited:
Just wanted to thank everyone for their contributions. AHC fluid change complete. Easier than bleeding brakes! I was surprised how dirty the fluid was with ~60k miles. It could be my mind playing tricks on me, but it does seem to raise and lower faster now.
Just don't give that to the baby now!
IndroCruise
SILVER Star
Have you tried McGeorge and Cruiser Parts?
AHC Suspension Fluid now Sold 2.5L Canister [08886-01805 now 08886-81221] - $60.49 : CruiserParts, The best place for Land Cruiser Parts!
CruiserParts AHC Suspension Fluid now Sold 2.5L Canister [08886-01805 now 08886-81221] - Automatic height control (AHC) suspension fluid, 2.5L Canister.5 liters needed to flush system of Land Cruiser or LX470 If you have any questions about the item(s) that you may need please feel free to call...
shop.cruiserparts.net
AHC Fluid is made (blended) in batches -- in a similar way to the way many lubricants are made -- and from time to time there can be localised shortages in various parts of the world.
This is a specialist low volume product -- but its use continues at least in ....
LC100 where AHC is fitted
LX470
LC200 where AHC is fitted and in KDSS
LX570
LC300 where e-KDSS is fitted
LX600
.... in markets where the above models exist.
So it is very hard to imagine that AHC Fluid has been discontinued.
At the moment, there are no shortages where I live (Australia) -- which I know is no use to you other than to know that AHC Fluid continues around the world.
Suggest ignore the web-site generated non-replies and persevere.
AHC Fluid is made for Toyota/Lexus by Japanese oil company Idemitsu Kosan Co Ltd.
You may wish to call or e-mail Idemitsu in USA and find out what the supply problem is in your part of the world -- USA contact details are within the links below.
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
Last edited:
Thanks for detailed response and info @IndroCruise . Dealer said they were out but can get it by tomorrow. My wife's cousin works for Toyota and he confirmed the plastic bottles have been discontinued and unopened stock from the dealer were to be returned as of December 2021. The 2.5L cans are still available, albeit in low production.
I panicked a bit when I was looking last night but then I realized they still use it in the 570 so it should be available for quite some time, it's just not a regular stock item.
I panicked a bit when I was looking last night but then I realized they still use it in the 570 so it should be available for quite some time, it's just not a regular stock item.
Does anyone have a recommendation on a decent bleeder valve kit?
I'm always using these el cheapo kits from amazon with low quality hoses and poorly gasketed connections to the wrench that leak so badly on my arms / garage floor out of the bleeder screw while I'm trying to get the old fluid into a bottle. It works but that creates a little chore for cleaning up the mess.
I'm always using these el cheapo kits from amazon with low quality hoses and poorly gasketed connections to the wrench that leak so badly on my arms / garage floor out of the bleeder screw while I'm trying to get the old fluid into a bottle. It works but that creates a little chore for cleaning up the mess.
What tubing do you like to use? I do not like the clear tubing that gets really stiff with age.
I just replace clear as it gets hard, with easy to find hardware tubing. Seems to last few years. Clear best, as can we watch for air bubbles.
I recently replaced two globes and while bleeding the fluid got below the minimum mark, but not empty. After topping off everything is in working order, although I am concerned about air in the system. Will lowering and raising the system push any air in the line out into the reservoir?
IndroCruise
SILVER Star
Posting error
Last edited:
IndroCruise
SILVER Star
Firstly, if the fluid level has not exposed the bottom of the AHC Tank and air has not been allowed to enter the AHC Pump, then there should not be a problem.
Q: “Will lowering and raising the system push any air in the line out into the reservoir?”
A: No.
The reasons are best understood by studying the hydraulic circuits under various conditions – suggest review the last few pages of the “AHC General Description” document attached at Post #242 in this thread (also posted in many other threads).
Then consider the following sequence of detailed steps which occur under the control of Suspension Electronic Control Unit (ECU) when lowering and raising an AHC-equipped vehicle:
Note that if air has entered the AHC Pump, then the AHC Pump may not start.
When eventually an air-affected AHC Pump is started (typically after multiple attempts and/or use of the “Active Test” procedure to 'prime' the Pump), then this is what happens when there is air in the AHC system:
1. The vehicle is lowered and the green AHC light on the dashboard blinks until the selected height is reached,
2. The ECU opens the Levelling Valves in the Control Valve Assembly and allows some (but not all) of the AHC Fluid in the ‘globes’, and, allows some (but not all) of the AHC Fluid in the ‘shock absorbers’, to flow directly to the AHC Tank via the Return Valve.
3. The AHC Fluid passes around but not through the AHC Pump to the AHC Tank – this allows the vehicle to lower,
4. If there is air in the AHC system, it is still there in the AHC Fluid and this polluted AHC Fluid is still present in the system even at “LO” height, as all of the AHC Fluid cannot be evacuated from the AHC system when lowering the vehicle,
5. Polluted-with-air fluid is now in the AHC Tank – some air may very slowly escape to atmosphere, some air will remain entrained/dissolved in the AHC Fluid in the AHC Tank,
6. Now raise the vehicle -- the green AHC light on the dashboard blinks,
7. The solenoid valve at the Height Control Accumulator is opened by the ECU and AHC Fluid flows under stored pressure from the Height Control Accumulator to the ‘globes’ and more importantly to the ‘shock absorbers’ which then wholly (or partially) raise the vehicle (depending on vehicle condition) – either from “LO” to “N”, or, from “N” to “HI”,
8. The AHC Pump starts under the control of the ECU and completes the raise until the ECU receives the relevant voltage signal from the Height Control Sensors for the height selected at the console switch,
9. When the raise is completed, the green AHC light on the dashboard stops blinking,
10. The AHC Pump does not stop but continues to run until it has re-charged the Height Control Accumulator with polluted AHC Fluid from the AHC Tank. Theoretically, re-charge takes about 15 seconds after the green light stops flashing for a new stock vehicle in good condition but can be longer, maybe 30 seconds, for an older or heavy vehicle,
11. When the Height Control Accumulator is recharged, the AHC Pump stops,
12. The polluted AHC Fluid has now been sent throughout the system, and, the Height Control Accumulator now has been re-charged with, and is full of, polluted AHC Fluid -- which will be sent again throughout the system when the vehicle is next raised,
13. The process then repeats from Step 1 above – the effect is that the polluted AHC Fluid is mixed throughout the AHC system.
If air is suspected in the AHC system, then removal of air pollution in the AHC Fluid requires bleeding as discussed earlier in this thread and elsewhere -- there is no avoiding this -- and persistent bleeding multiple times may be required.
Q: “Will lowering and raising the system push any air in the line out into the reservoir?”
A: No.
The reasons are best understood by studying the hydraulic circuits under various conditions – suggest review the last few pages of the “AHC General Description” document attached at Post #242 in this thread (also posted in many other threads).
Then consider the following sequence of detailed steps which occur under the control of Suspension Electronic Control Unit (ECU) when lowering and raising an AHC-equipped vehicle:
Note that if air has entered the AHC Pump, then the AHC Pump may not start.
When eventually an air-affected AHC Pump is started (typically after multiple attempts and/or use of the “Active Test” procedure to 'prime' the Pump), then this is what happens when there is air in the AHC system:
1. The vehicle is lowered and the green AHC light on the dashboard blinks until the selected height is reached,
2. The ECU opens the Levelling Valves in the Control Valve Assembly and allows some (but not all) of the AHC Fluid in the ‘globes’, and, allows some (but not all) of the AHC Fluid in the ‘shock absorbers’, to flow directly to the AHC Tank via the Return Valve.
3. The AHC Fluid passes around but not through the AHC Pump to the AHC Tank – this allows the vehicle to lower,
4. If there is air in the AHC system, it is still there in the AHC Fluid and this polluted AHC Fluid is still present in the system even at “LO” height, as all of the AHC Fluid cannot be evacuated from the AHC system when lowering the vehicle,
5. Polluted-with-air fluid is now in the AHC Tank – some air may very slowly escape to atmosphere, some air will remain entrained/dissolved in the AHC Fluid in the AHC Tank,
6. Now raise the vehicle -- the green AHC light on the dashboard blinks,
7. The solenoid valve at the Height Control Accumulator is opened by the ECU and AHC Fluid flows under stored pressure from the Height Control Accumulator to the ‘globes’ and more importantly to the ‘shock absorbers’ which then wholly (or partially) raise the vehicle (depending on vehicle condition) – either from “LO” to “N”, or, from “N” to “HI”,
8. The AHC Pump starts under the control of the ECU and completes the raise until the ECU receives the relevant voltage signal from the Height Control Sensors for the height selected at the console switch,
9. When the raise is completed, the green AHC light on the dashboard stops blinking,
10. The AHC Pump does not stop but continues to run until it has re-charged the Height Control Accumulator with polluted AHC Fluid from the AHC Tank. Theoretically, re-charge takes about 15 seconds after the green light stops flashing for a new stock vehicle in good condition but can be longer, maybe 30 seconds, for an older or heavy vehicle,
11. When the Height Control Accumulator is recharged, the AHC Pump stops,
12. The polluted AHC Fluid has now been sent throughout the system, and, the Height Control Accumulator now has been re-charged with, and is full of, polluted AHC Fluid -- which will be sent again throughout the system when the vehicle is next raised,
13. The process then repeats from Step 1 above – the effect is that the polluted AHC Fluid is mixed throughout the AHC system.
If air is suspected in the AHC system, then removal of air pollution in the AHC Fluid requires bleeding as discussed earlier in this thread and elsewhere -- there is no avoiding this -- and persistent bleeding multiple times may be required.
Last edited:
Thanks for the detailed response!
7 is most likely failed globes. So I don’t think 8 is a great figure.
Taking all the following comments into account may I make another suggestion for future readers of this thread. After studying and only after studying the process, in the event you have a wrung-off bleed nipple, one other option is to forget about trying to get it out but using the Trouble Solving process called The Active Test, you could activate this process and lower your cruiser down to the lowest it will let you go. This process actually lowers the cruiser lower than Lo thus pushing even more old fluid up into the AHC RESERVOIR. THEN suck out all the old fluid out of the reservoir and immediately replace with the New Fluid. Granted this might not get just as much old fluid out of the system but I’m led to believe it’s a pretty good alternative option with getting almost all of the fluid removed. Remember you can then step out of active mode and then bleed the Accumulator and the other three wheels as per the PADDO schedule. Please research my suggestion thoroughly, perhaps seeking advice from a veteran MUD specialist such as PADDO or UhU to name but only 2 of the excellent folk on this Forum.