Based on your tests, I would suspect the solenoids as well.
What's the resistance of the coils?
After removing them, see if there's any debris down inside.

Chip H.

 

Hi Chip, which coils are you referring to and where are you suggesting looking for debris? There seems to be limited info about solenoids online :/

I was able to locate a section of the service manual that contains the resistances and testing procedure for the solenoids, so I plan to take a crack at that next week.

 

The magnet coils in the solenoids.
If you have the procedure, follow that.

Chip H.

 

Just a brief(-ish) update from me, below is the page I am using to test the solenoids and a description of the circuit. I ended up deciding not to remove the tank from the car, and to test it in place since the connector was easily accessible. It seems my gate solenoid (which controls the flow between left and right bags) is indeed stuck!! I got 11 ohm resistance between 2-3 (leveling solenoid) and 19 ohm from 1-2 (gate solenoid) however applying 12v from a 12v power supply produced a click from 2-3 and silence from 1-2. Checked my connection 3 times.

Now I just need to figure out how to unstick it.... any suggestions/help would be appreciated.

Side note: of course I end up with the most obscure failure in the system :/ hopefully this info can help someone else in the future.

 

There's a air control box mounted up underneath the rear driver side. That control box collects dirt over time. Remove it and carefully take it apart and clean it.

 

Sorry are you referring to the reservoir/circular tank with the solenoids on it?

I ended up giving the solenoid 12v and tapping it with a vice grip and it unstuck, though it did get stuck again later, and all my issues are still present (uneven height, leaks down overnight, will not exhaust air and lower)

 

I also ordered a techstream cable to dig deeper.

 

I am happy to report my rear is level again! The fix was to disassemble the reservoir and clean it. My gate solenoid kept getting stuck even after unsticking it, and I suspect airflow was impeded as well.

Before disassembly I hooked up techstream, and I was able to toggle every solenoid and hear them click (with the gate occasionally sticking), and see the height sensors were reading sane values. I adjusted the height sensors to be equal while the car was on bump stops.

There are 2 10mm bolts holding the solenoid assembly to the reservoir. I suggest applying 12v to open the reservoir solenoid and letting the air out before removing. There is an o ring between them so pull out the solenoid assembly carefully. Next there are 4 hex bolts I removed to separate the plastic air channels from the solenoids. There is one o ring per solenoid between the plates. These are also on springs so be careful everything doesn't fall out when you separate the plates. I cleaned each solenoid plunger with a wire brush and brake clean. I checked the springs and sprayed some silicone lube in each hole. On the plastic side I used a sim card removal tool to clean out the tiny holes, MAF cleaner, and compressed air.

Here are some pics of it disassembled.




I still need to track down my leak, and my compressor's exhaust valve is intermittently sticking, but those should be a walk in the park compared to this *knock on wood*

 

Nice work!

Chip H.

 

Hello. Thanks for the informative thread. I'm doing some work on my GX470 air suspension as well. I Have a question that's related to some of the recent posts in this thread, that I haven't seen addressed in the many threads I've read. I'm wondering about some specifics of the air suspension operation i don't seem to see in the FSM. My GX leans to the passenger side. To address this I've tried adjusting the height sensor linkage to a different position on the right side than the position of the linkage on the left side, hoping this would bring the right side to the same level as the left. It didn't seem to have this effect. Can the system direct the gate solenoid to deliver more air to one spring to level the vehicle from side to side? Could you intentionally cause a lean to one side by adjusting one sensor to a considerably different position than the sensor on the other side? If so, I'd think this would be an ideal solution to the KDSS lean that many GX's have. I'm just generally wondering what logic the system operates on. I'd appreciate any enlightenment on the matter. Thanks much.

 

Yes, each side has a solenoid valve. Verify your height sensors are good. After that you should clean the solenoid valves as described in this thread.

 

Post #548.
Good work.
Every 470 needs that control "box" cleaned out and re-lubed properly. It collects dirt over time. Mine is past due for a 2nd cleaning.

 

Thanks much for the reply. It makes sense the system should have the ability to inflate each side to different levels. I think i had at least one part that may have been interfering with this though. This weekend I opened and cleaned the solenoid assembly and both height sensors. Everything looked pretty good. I had earlier replaced the right height sensor linkage, which had a frozen ball joint on it. This caused the nut that attaches the link to the upper trailing arm to keep coming loose, which allowed the link to keep sliding to different positions in the adjustment slot. I also used Techstream to test the various solenoids and match the height values of the left and right sensor to one another while the vehicle was positioned perfectly level. I'd also replaced the right height sensor itself the week before, which got damaged while I was replacing the linkage. I replaced it with a unit pulled from an 05 Prius, which uses it to adjust the aim of the headlights apparently. It's the exact same part, with the same resistance values, though it's often not cross referenced. I'll paste a list of early 2000's lexus/toyota vehicles that use it. Many are fairly easy to find at self service salvage yards, and likely see easier lives than the GX units.

Application:
Compatible with Lexus ES330 2004-2006 V6 3.3L Sedan
Compatible with Lexus ES300 2001-2003 V6 3.0L Sedan
Compatible with Lexus IS300 2001-2005 V6 3.0L Wagon/Sedan Front; Rear
Compatible with Lexus RX330 2004-2006 V6 3.3L Sport Utility Rear Right AWD
Compatible with Lexus RX330 2004-2006 V6 3.3L Sport Utility Rear FWD
Compatible with Lexus RX350 2007-2008 V6 3.5L Sport Utility Rear Right AWD
Compatible with Lexus RX350 2007-2008 V6 3.5L Sport Utility Rear FWD
Compatible with Lexus RX400h 2006-2008 V6 3.3L Sport Utility
Compatible with Toyota Tacoma 2005-2008 L4 2.7L Pickup
Compatible with Toyota Tacoma 2005-2008 V6 4.0L Pickup
Compatible with Toyota Prius 2004-2009 L4 1.5L Hatchback
Compatible with Mazda RX-8 2004-2008 R2 1.3L Coupe Front; Rear

OEM Number: 89405-48020, 89406-53010, 89407-48010, 89407-48030,89408-47010, 924-755

 

I disagree with this. If you read the descriptions from the service manual i posted a few posts up, I do not believe the system is able to send air to a specific bag. While filling i opens the gate solenoid, which allows air to flow between the 2 bags. There is not a solenoid for the left and right bags.

i could be wrong, but this is my interpretation and understanding.

 

How many valves are in that box? It only needs two valves if the bags are in same airline, one for a fill, and one to release.

I too could be wrong. If it's not independent then why are there two height sensors?