After towing LX 2500 miles AHC won’t go into high. (2 Viewers)

[Kabanstva]

Was it you that said they had 300lbs hanging off the rear bumper or was it @Sventvkg?

Just because it's "heavy duty" doesn't mean that you can neglect it, hang a bunch of weight off the rear bumper and expect to get away with it. You don't like AHC, that's fine. Neither did I until I learned how it works and how to maintain it.

Fair enough. I’m still waiting for someone to explain why my ahc fluid just disappeared that one time. And it wasn’t me that said they had 300lbs hanging off their bumper. I maybe had that much weight inside the trunk but nothing hanging off the bumper.

 

[suprarx7nut]

It seems to go into high, but then comes back down into low. I know I have needed to change the fluid and I’m going to get to it very soon, but is there any other reason you can think of that it won’t go into high? It also doesn’t feel the same. It’s more spongy like the comfort setting Isn’t responding either. Did I mess up a sensor? Any insight appreciate it thank you.

EDIT:
I just realized I have a hitch cargo rack on the back with probably 300 pounds worth of stuff, a generator and a couple bins. Could that have something to do with the front going up in high but then coming back down? The back doesn’t move.

This is a bit of a facepalm moment and an indication that AHC knowledge still has a ways to go.

Yes, your added weight on the hitch is preventing the car from raising to H. Chances are about 99.99% that your neutral pressures are too high (disregarding your current added weight) and the initial ~1000 lb payload capacity has been reduced to something closer to your current hitch weight.

Connect a device that can read pressures. Adjust T-bars (30mm socket) and move on happily.

What do you consider maintain? My LX had the fluid changed several times throughout its life. I bought it with 116k miles, from the original owner. My brother was their service adviser at Lexus since day one. Every recommended service was always done. What exactly do you consider neglect? Spending thousands replacing globes and all that other crap in the system? Edit: vehicle was only 8-9 years old when I bought it so far from old by Toyota standards…and remember the whole 25 year cycle they claim with Land Cruisers….

For AHC, checking pressure and adjusting T-bars fundamental maintenance. It is often neglected, which is silly because it's easier than changing engine oil.

As I recall in your situation, a pressure check and adjust was never performed while you owned it (please correct if I'm off-base). That's why you had height problems. All you needed was a 5 minute T-bar adjustment. For free. lol.

If you don't check and adjust neutral pressures on an AHC vehicle, it will fail to go into H - EXACTLY the same as when a conventional suspension squats with added weight. It's literally the exact same phenomenon except that AHC has the unusual capability of perfectly leveling up to roughly 1000 lbs above and beyond the neutral pressure calibrated weight.

There are AHC failures where a line ruptures or a pump fails, but those are quite rare. Far more common is that an owner is oblivious to the 5 minute adjustment that should be done every few years or when you add a significant weight modification (exactly the same as you should correct conventional springs when you add weight).


This is a frustrating topic for AHC because AHC gets punished for being better.

With conventional suspension: Add weight. Immediately visible squat. Add more weight. More immediately visible squat. Add too much weight. Riding on Bumpstops as expected.
Owner reaction: "Wow, I should probably update the springs or lighten up the car. No problem!"

With Adjusted AHC: Add weight. ZERO squat. Add more weight. Still ZERO squat. Add too much weight. Riding on Bumpstops as expected.
Owner Reaction: "I hate this overly complex, useless suspension. It just randomly FAILED one day. What garbage."


This is why we can't have nice things.

 

[GTV]

Fair enough. I’m still waiting for someone to explain why my ahc fluid just disappeared that one time. And it wasn’t me that said they had 300lbs hanging off their bumper. I maybe had that much weight inside the trunk but nothing hanging off the bumper.

The disappearing fluid is an interesting one. It went somewhere. If not on the ground it’s usually in the “shocks” and the rig is in high (front and/or rear, intentionally or not) and riding like crap. In my case that was the front height sensors.

I totally get not wanting to think about your suspension, just set it and forget it.

 

[GTV]

This is a bit of a facepalm moment and an indication that AHC knowledge still has a ways to go.

Yes, your added weight on the hitch is preventing the car from raising to H. Chances are about 99.99% that your neutral pressures are too high (disregarding your current added weight) and the initial ~1000 lb payload capacity has been reduced to something closer to your current hitch weight.

Connect a device that can read pressures. Adjust T-bars (30mm socket) and move on happily.



For AHC, checking pressure and adjusting T-bars fundamental maintenance. It is often neglected, which is silly because it's easier than changing engine oil.

As I recall in your situation, a pressure check and adjust was never performed while you owned it (please correct if I'm off-base). That's why you had height problems. All you needed was a 5 minute T-bar adjustment. For free. lol.

If you don't check and adjust neutral pressures on an AHC vehicle, it will fail to go into H - EXACTLY the same as when a conventional suspension squats with added weight. It's literally the exact same phenomenon except that AHC has the unusual capability of perfectly leveling up to roughly 1000 lbs above and beyond the neutral pressure calibrated weight.

There are AHC failures where a line ruptures or a pump fails, but those are quite rare. Far more common is that an owner is oblivious to the 5 minute adjustment that should be done every few years or when you add a significant weight modification (exactly the same as you should correct conventional springs when you add weight).


This is a frustrating topic for AHC because AHC gets punished for being better.

With conventional suspension: Add weight. Immediately visible squat. Add more weight. More immediately visible squat. Add too much weight. Riding on Bumpstops as expected.
Owner reaction: "Wow, I should probably update the springs or lighten up the car. No problem!"

With Adjusted AHC: Add weight. ZERO squat. Add more weight. Still ZERO squat. Add too much weight. Riding on Bumpstops as expected.
Owner Reaction: "I hate this overly complex, useless suspension. It just randomly FAILED one day. What garbage."


This is why we can't have nice things.

Gold.

 

[jOnathN]

Re normal maintenance: about every 100k-150k miles you will need to replace the globes. Same as replacing normal shocks on any vehicle - typically the same interval. The globes cost the same as new shocks also (more expensive parts, less expensive labor)… since you can swap them in ~5 min each in the driveway with pliers and a strap wrench. If you do that, and ideally check neutral pressures at the same time, you’ll be fine.

If you carry a lot of extra weight all the time, bumpers and gear, whatever, then you will need to beef up the springs… same as with a standard suspension.

 

[TexLXCRZR]

I am at a crossroads with my AHC - have a small sensor lift - have replaced all control arms, globes, fluid.

Only items left are the shock bushings for a complete refresh. The occasional random ride height adjustments concern me as well as a feeling that ride quality varies day to day. I wonder how much wear has occured to the contacts in potentiometer based ride height sensors or increased resistance in all the wiring - difficult to quantify but what I love about the 100 series is durability/reliability and the last thing I want is an odd suspension failure out in the middle of nowhere. My truck spends the majority of time on pavement so I enjoy the ride quality as well.

Diminishing others legitimate concerns about a system with a 10x complexity and potential failure points is not helpful just as wholesale trashing AHC doesn't serve our community.

Anyone who has switched to conventional regret it and wish they still had AHC? considering an OME tbar/spring and either Bilstein or Fox shocks likely