Yonny

I know this day would eventually come since I got the car.
But the question is how likely is that both start leaking air the same day.

Last night I saw the nose almost touching the ground from the whole front, left and right wheel arches completely filled by the tyres as there was no gap between them.

So I was thinking perhaps there is a common part that keeps the air pressure for both corners that is really the cause of the leak.

Or is just a huge coincidence that both air suspension shock absorbers went the same day ?

RA40

iTrader: (6)

There is a leak so neither of the front can be pressurized as far as I'm aware. Year of car and how many km/miles?

Yonny

99 120k.

It does keep the pressure for about 5 hours. Takes less than a minute to fill up both corners. Rides ok, feels like always. The only difference is that it looks slammed when I go in the morning.

Yamae

I would check the air leak at the height control valve for the front spraying some soap water. See the drawing below although it's from a JDM manual and words are in Japanese. Top two arrows in the lower box indicate joints to the front right and the left air bag. The height control valve is attached right next to the air pump. You can find it removing the fender liner.

Yonny

Thanks I will check on that tomorrow and report what I find.


Air suspension system
I will follow the English version XD.

Yonny

Last night I put a jack stand under the right front corner only. But both corners were up right. If there was a leak in the valve out of the compressor, I thought the left front side would have been low since the jack stand was on the right front.

But as soon as I removed the jack, the whole front lowers.

So when the right side only is supported, both sides keep the level, and when I remove the support for the right side both sides lose its level.

Yonny

Looking for some parts in case I need to replace them I found this.

Looks a little bit different.

But the seller told me it's compatible with my car.


Ls400 air suspension

Ls400 air suspension

Ls400 air suspension

Ls400 air suspension

Ls400 air suspension

Yonny

So last night I jacked the car and placed a stand only on the left front side. Left it there for about 11 hours and this morning I saw both sides were completely up right. Removed the jack stand and began to lower the cat with the jack slowly, then I realized the left side was keeping the normal riding level, but then went to the other side and saw the right side was Also at its normal level. I was expecting both sides to lose its level and the whole front get slammed. This is weird.

Tonight I will put a stand again only on the right front side and check tomorrow morning, then report back What I find.

Yonny

Last two nights I placed the stand on the left side only and removed it in the morning. Both times the car held its normal driving level when the stand was removed because the air didn't leaked.
But as soon as I leave the stand over the night on the right side also, the air leaked and so the whole nose get slammed when removing the jack stands. Same happen if the jack stand is placed on the right side only.

Any ideas why this happens.

So far I haven't find where the leak is.

Yonny

This is what I have found so far.

Very weird but its been confirmed several times.
I use the car, park it while the suspension is extended to its normal driving level, I switch the engine off and jack the car from the left front. Leave it there for 10 hours, then I come back next morning.

Car jacked up> left front supported > engine off all night > remove stand while engine still off> both front shocks absorbers hold and the whole nose keeps its normal driving level as it was the previous day.

Car jacked up> left front supported > engine on for a few seconds> remove stand while engine is on> both shock absorbers lose the air and the whole nose slams to the ground while I lower the car with the jack.

I have to say the car while is on the stand is higher than the normal driving level. So I think as soon as I start the engine some sensors tell the computer to leak the air.
But while the engine is off this sensor is not working.
The sensor that activates the air pump registers the height of the nose independently from left to right. If one corner needs air and not the other, it only pumps that corner.

Yamae

Reading your posts, I now have 2 questions.
How often the pump motor work when you are driving?
Have you tried to read the error code for the air suspension?

deanshark

I can't diagnose your exact problem but I'll tell you on my 93 with factory air the sensors did not work with the key off. It would raise or lower as soon as I turned the key on in the morning. Each corner has it's own sensor for the height. Only 2 of the same sensors are used for your self adjusting headlights.
Not sure how much different the 99 is from the 93 but I had the shut-off switch in the trunk to turn off when the car gets jacked up. If you have that switch, have you tried turning it off to see if the front doesn't lower over night?
During the day: can you hear the compressor turning on at all? (try parking on a hill or with the car on an angle) Have you tried looking for leaks as described above?
I had 2 shocks that leaked. (1 front 1 rear) As soon as that happened, I had no second thoughts I immediately changed to the conversion shocks. Too much can go wrong with the air and too much time can be wasted trying to find what's wrong. (Just an observation)
Here's the suspension part of the 2000 manual. (Thanks to bradland )

Yonny

I have seen the front rise while stopped on a traffic light a few days ago only once. But its really hard to spot that movement as it is very slow and quiet.
I think not very often hear the compressor. 90% of the pumping action happens when I start the engine in the morning before I start moving forward. I don't think the pump starts if the car is rolling. But again I am not sure because this compressor noise can blend easily with the road noise and wind noise at very slow speeds.
I will check again for code errors later. I did it the first time I saw the problem but didn't find anything.

Regarding the switch, I am not sure where to look at. Can you share a picture of the area where the switch is in your car? Thanks.
And about leaks, I haven't check every spot possible. Only the top of the shocks absorbers. Haven't check out the compressor itself yet. But will do it as soon as possible.

Last night I parked the car while the suspension was fully extended to its normal driving level and jacked up only the right side.
Later today when I get to work I will remove the stand while the engine is off and see if the same happens as when I jack the car on the left side.
Because I can't recall if the engine was on or off every time I jacked up the right side only, and I want to see if the state of the engine has a consequence to the leak while the engine is off.

deanshark

The shut-off switch on my 93 was in the trunk inside the tool kit door on left side.

Yonny

I haven't find the switch. On the 99 the tool kit is on the right side. But I looked at both sides and didn't see anything looking like a switch.

Today and yesterday I placed the jack stand on the right side only. And it behaves like it does on the left side.
If the engine is turned off while I remove the stand and lower the car, both front shocks absorbers keep their normal driving level.
So the leak only happens when neither of the shocks absorbers are held by a jack stand, or when I turn on the engine before I remove the jack, probably because the height of the car is higher than what it would be on its own, and a sensor perhaps is telling the computer to leak the air as soon as I start the car l, because it takes me about a minute to remove the stand after I start the engine. During this period I think the car leaks all the air pretty quickly.