Lexus AHC works the same. Manual adjustment is possible if you're moving slowly or if you're stopped and the brake pedal hasn't been pressed too long.
AHC: what are the pros/cons?
- Thread starter jumptrader
- Start date
This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.
Maybe it can go into low when I am driving but will not go into high unless parked. And you are probably right I may not have needed as much as I did but like I said I am more cautious than most. And I agree it is nice that when you put it into high you get that lift no matter your load. With a traditional you are stuck with whatever height it sits at when fully loaded.
If you truly believe you need to stay in "H" above 19MPH, you can install the Slee override switch and keep it in "H" as long as you want.
That's not normal behavior. My LX definitely changes height in drive. According to the manual, it should be reverting back to high as soon as your speed slows.
If yours really does not return to high while moving, I think something is off.
Were you in 4Lo?
Agreed. Similar approach for me when I pull into my garage.
Good question. I found the install instructions. Worth giving them a call if it's something you need.
Interesting I will have to go do some testing tonight.
It should stay in H until 30 MPH or more if you are in low range. Your pump may be failing and not able to build enough pressure to raise the truck while it's moving, does it make any noise?
uHu has summarised AHC features in posts #4 and #7 in this thread. This Toyota attachment also may help:
If you're in a situation where you really need high mode, you should probably also be in 4Lo, but I can understand the desire to stay in H and play it safe.
The Slee over-ride switch sounds like exactly what you want, if you can find it.
I have ran almost all aftermarket suspension brands from the last 14 years on different pickup trucks and suv, even the ones from Thailand and China. The AHC is by far the best in terms of ride comfort and convenience of adjusting damping/rebound resistance settings on the fly (IMO better than Rover’s air suspension in terms of ride comfort and reliability).
CONS - if you are not fond of going under the vehicle to drain the AHC fluid for its routine PMS drain & flush, it can be a little hassle.
CONS - if you are not fond of going under the vehicle to drain the AHC fluid for its routine PMS drain & flush, it can be a little hassle.
That's a great read thanks.
@suprarx7nut you where right. My LX can switch to H or L while driving. I am just an idiot. It cracks me up all the times I stopped to switch my height while on my trip this past summer.
AHC is a fully active suspension only added to higher end vehicles because it is an expensive technology. It's most famous counter part is actually used in Tanks, the hydro-pneumatic suspension developed by Citroen which I'm sure Toyota bench marked due to its similarities
You have guys who get wet for the KDSS (looking at you GX470 guys) which is a semi-active suspension but provides many of the Active suspension capabilities, why not the same response to a more superior and technologically advanced suspension, maybe lack of understanding?
Toyota has managed to give us a fully active suspension that for the most part is a reliable beast with many examples reaching 20 years and 200k miles with no service ever done and still functional. Read resident expert @PADDO 's extensive posts on the AHC system and replace the fluid, replace the rear springs, adjust torsion bars and you are likely set for the next decade if you had functional system. You will then be rewarded with a system that is capable of the following:
1. Self-levelling and height adjustment
2. Pitch and roll mitigation
3. Pitch and roll control for improved aerodynamics/lean into curves
4. Handling enhancement
5. Comfort enhancement
6. Road friendliness
I just read parts of a PHD's extensive thesis on Active Variable Geometry Suspension for Cars by Carlos Arana Remirez Submitted in part fulfillment of the requirements for the degree of Doctor of Philosophy Imperial College London Electrical & Electronic and Mechanical Engineering Departments Control & Power Research Group London, United Kingdom September 2015
You guys have to check this out its a really good read talking about the technology dating back to beginning of automobiles.
https://spiral.imperial.ac.uk/bitstream/10044/1/41040/1/Arana-C-2016-PhD-Thesis.pdf
Some quotes:
You have guys who get wet for the KDSS (looking at you GX470 guys) which is a semi-active suspension but provides many of the Active suspension capabilities, why not the same response to a more superior and technologically advanced suspension, maybe lack of understanding?
Toyota has managed to give us a fully active suspension that for the most part is a reliable beast with many examples reaching 20 years and 200k miles with no service ever done and still functional. Read resident expert @PADDO 's extensive posts on the AHC system and replace the fluid, replace the rear springs, adjust torsion bars and you are likely set for the next decade if you had functional system. You will then be rewarded with a system that is capable of the following:
1. Self-levelling and height adjustment
2. Pitch and roll mitigation
3. Pitch and roll control for improved aerodynamics/lean into curves
4. Handling enhancement
5. Comfort enhancement
6. Road friendliness
I just read parts of a PHD's extensive thesis on Active Variable Geometry Suspension for Cars by Carlos Arana Remirez Submitted in part fulfillment of the requirements for the degree of Doctor of Philosophy Imperial College London Electrical & Electronic and Mechanical Engineering Departments Control & Power Research Group London, United Kingdom September 2015
You guys have to check this out its a really good read talking about the technology dating back to beginning of automobiles.
https://spiral.imperial.ac.uk/bitstream/10044/1/41040/1/Arana-C-2016-PhD-Thesis.pdf
Some quotes:
My answer: Irrational fears of erroneous repair estimates from mechanics that don't understand the system and don't understand how to diagnose it.
The internet has helped exaggerate and proliferate these [IMO, falsely based] concerns and now there's a significant amount of content on the internet that basically says, "if your AHC has any minor problem throw it away immediately."
In reality, AHC in very simple terms is an on-demand lift of 2+ inches with a ride more comfortable than any other suspension system available at any price point. It offers a lift when you need it without the objective faults of traditional permanent lifts. Increased CV wear (or reduced ground clearance if you drop the diff to compensate), poor highway handling capabilities, restricted access to parking garages and low clearance driveways, etc...
- The rams (shocks) very rarely fail and are reasonably priced at ~$230 each.
- The accumulators need replacement a little less often than traditional shocks and cost a similar amount (compared to aftermarket performance shocks)
- The pump very rarely fails.
- The lines very rarely fail unless the undercarriage is severely rusted.
- Torsion bar adjustments are free.
- Rear springs are ~$325 per set and needed once every ~10 years
Okay so my bushings at the top of my rear shocks have gone I believe. I am going to lift it this weekend but I believed this is the source of some clunking when going over any type of bump.
If it is the bushings do I need to replace the whole shock or can you do just the bushings?
Secondly is it possible on a rust free vehicle to get the shock off?
Thirdly I can put in a dobinsom suspension for 997. New shocks and springs will cost me around 850. Should I do a full swap out? I will be adding front bumper with winch, bumper and a gamiviti roof rack. So if I don't replace what will I need to do to help the ahc out?
If it is the bushings do I need to replace the whole shock or can you do just the bushings?
Secondly is it possible on a rust free vehicle to get the shock off?
Thirdly I can put in a dobinsom suspension for 997. New shocks and springs will cost me around 850. Should I do a full swap out? I will be adding front bumper with winch, bumper and a gamiviti roof rack. So if I don't replace what will I need to do to help the ahc out?
uHu
Bridgeburner
The lower bushings wear out faster than the tops. Put the ahc in Lo first, then jack up -- in order to not have pressure on the shock (ram). Then check lower and upper bushings.
No need to change the shock unless it's leaking severely.
Should be OK, but it's damned tight. Remove spare wheel and get the best tools for the job (search this forum). Easiest is to cut a hole above.
No need to change shocks. If only adding weight up front, you should be OK with tightening the torsion bars. Might need a re-indexing. You do need to use TechStream or similar to get the ahc pressure right.
I have to agree with a lot of what you said. The system seems scary and expensive at first, but now that I've learned about it I plan to keep it as long as possible. Even full glob replacement can be done for about $1300 with OEM parts. I bought new rear springs a few months ago from McGeorge and only paid about $100 per side, maybe $220 total after shipping.
