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Air Suspension


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I have a question about my air suspension in my 03 LX which I just bought recently.

I would like to have it in low because I'm just doing fast city driving most of the time and I want better performance and gas milage and it is also harder from my mom to get into when it is up high. When I put it in low, the light starts blinking, I can feel it moving down, and I wait for the light to be solid and all the movement to stop. Everything seems fine and normal so I back out of my driveway and start driving, problem is it goes right back in the Normal as soon as I start to accelerate. Why wont it stay in low? I've tried everything. I've tried putting it in low and then turning it off but it just goes back into normal while I'm driving. Is there something I need to do to make it work correctly?

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Doesn't anyone else have a Lexus LX? Or are all you lexus owners just lazy and rude?

whoa man. seems like you're the only lexus owner here that's rude. if you want an answer, lose the attitude and have some patience. not everyone has time to visit the forum constantly to respond to your posts.

now for your answer: you can manually lower and higher the suspension, but it will automatically return to "N" when your speed goes above, im not sure about this, but i think its around 10 mph. it will return to normal even if you put it into "L"and then turn the AHC off. the only way to get around this is to buy an aftermarket AHC controller that you will need to wire in, such as this (scroll down to AHC controller). but you will need to pull up the trim surrounding the shift lever and then wire it in. after that you will need to find a place to mount the switch, as this controller is controlled by a switch. you can wire the switch in the empty button slot next to wear the rear defroster switch is (that's how it is in the 98). but like i said this is involved and may not be the best idea if you do not know much about this.

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Take it easy. Have you tried the search function of the forum? That's usually the reason why other members don't feel like answering old questions that were discussed NUMEROUS times in the past, but I will try to help you...

The air suspension is designed to stay in "N" when the vehicle is running over 20mph. Why? It was programmed that way. The reason why you can raise the suspension is because of more ground clearance for offroading and the reason for lowering the suspension is the ability to easily (although it doesnt help much) get in and out of the car, or load and unload heavy stuffs into the car. Otherwise I'm not sure how you can bypass that 20mph program so you can drive in low height while driving.

wow coincidentally another member just replied while I was typing my reply... :wacko:

Edited by denslexusgx470
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First of all, the LX suspension is hydraulic, not air. Second, it's designed to go into N above 9 mph (yeah, the manual says something like 18mph, but that's a typo). The L mode is mostly to facilitate easy loading/unloading of the vehicle or connecting/disconnecting a trailer. Keep in mind that with any independent front suspension vehicle, if you install a controller and keep in it in low almost all the time, you should have the front end realigned for that low setting. Also, you will be losing most of your suspension up travel, so if you hit a speed bump, you could bottom out the suspension...not good.

As for controllers, there are a number on the market. The only one I've seen made in this country is offered by Slee offroad, looks a little crude. Other ones sold in Japan can get pretty advanced. The basic one is a model by BBlanks that allows one to lock the AHC in L, N, or H, regardless of speed. This type is a AHC ECU replacement, I think (goes inside your dash), so you use the same factory switch in the center console to raise/drop the vehicle. Other ones are a controller box. A couple of them (about $500) allow you to raise or drop the front or back independently in 10mm increments.

As far as how the LX suspension works, there are two parts. One is a height actuator ( the cylinder under the driver's side frame rail) that raises the vehicle (sensors at the front & back tell the AHC if each corner is at the proper height) by pumping AHC fluid into the shocks. Then there's the hydraulic damping system, which consists of one "globe" module connected to an accumulator at each wheel. The globes are partly filled w/ nitrogen, and there's a membrane inside that separates the nitrogen from the AHC fluid. I believe it works something like this. The accumulator has a valve that constricts or dialates according to the setting from comfort to sport. When dialated, more fluid can enter the sphere and move the membrane to compress the nitrogen for a softer ride. When the orifice constricts, less fluid enters the sphere, and the ride is firmer.

The AHC also has a max load. Passenger + cargo weight cannot exceed about 660 lbs or the AHC will default to L regardless of speed. What sets it off is a hydraulic pressure sensor inside the AHC pump. If the load is too high, the pressure increases, passes the threshold, and the systems reverts to limp mode to prevent damage.

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