ASE

The one thing that's nice about the rear air bag "springs" is that the rear ride height can be dialed in to exactly match a slightly lifted front ... by moving the neutral position of the height sensor. Rear springs typically come in 1" height increments for a lift... with 2" being the most common. Yes, you can install rear 4-Runner or FJ Cruiser springs ... but until installed, the resulting ride height will be not exactly known.

Qwertym3

Hello everyone. I am new to the forum and to the GX470. I acquired one last December 2021. It was working great when I got it and I really like the ride with the air suspension. However, the ride has now become bumpy and I suspect that a component is broken.

Below are some of my observations:
- the air bags seem to be deflated (the bags are folding down to the base plate)
- the compressor does not turn on when I start the car
- the height control led in the dashboard is in normal
- the compressor turns on when I press the High setting (green led blinks then stops after some time) but it does not seem to do anything. I did not notice any actual height adjustments.
- the car is very bumpy when riding up and down sloping roads. It gets better on the highway but it becomes bumpy again in uneven areas

Context:
- air bags are new Arnotts (2-3 months old when i got the car in December)
- the battery drained after about 2-3 weeks of the car not being used (because of the bumpy ride)
- the height adjustment used to remain in the normal position even if I press the High button. This was resolved by doing the pin shorting trick (under the driver dashboard panel) I found in Youtube. But the resolution only made the H led blink green and start the compressor but no actual height adjustment happened.

Questions:
1. Does the air suspension compressor always run whenever you start the car? Or only when the car is started and the sensors detect abnormal height?
2. Does the compressor run automatically even when the car is turned off and parked to correct abnormal height detected (why my battery drained)?
3. If the compressor is overworked does it have logic to stop working until the issue is fixed (why the height adjustment did not move to the high position) and why it no longer inflates the bags.
4. I have read that there is a relay switch for the air suspension system, where can I find this relay so I can inspect/replace it?
5. Do you have ideas what could be the problem? I suspect broken height sensors so I plan to check them soon.

This is a picture of one of the air bags:


Thanks in advance for your answers or comments.

Davenlei

iTrader: (1)

Here are some answers to your questions based on my knowledge with my 2008:
1. Does the air suspension compressor always run whenever you start the car? Or only when the car is started and the sensors detect abnormal height?
Answer: It only kicks on when the sensors detect the ride is not at the correct height. If it used to kick on every time you start the car then you probably had a leak in the air system somewhere.
2. Does the compressor run automatically even when the car is turned off and parked to correct abnormal height detected (why my battery drained)?
Answer: No. It should not kick on when the car is parked and not in use.
3. If the compressor is overworked does it have logic to stop working until the issue is fixed (why the height adjustment did not move to the high position) and why it no longer inflates the bags.
Answer: No. It will run until it kills itself. It will continue to run while the car is on until the ride height sensor identified the vehicle is at the correct height. That is why the advice here is to resolve leaking air systems as soon as possible to avoid damage to the compressor.
4. I have read that there is a relay switch for the air suspension system, where can I find this relay so I can inspect/replace it?
Answer: I believe there is a relay in the fuse box in the engine compartment if my memory serves me right.
5. Do you have ideas what could be the problem? I suspect broken height sensors so I plan to check them soon.
Answer: Usually it is leaking air springs or damaged/loose ride height sensors. I would say 95% of the time it seems as if it is an air spring with a very small leak.

ALAN553

leaky air springs lead to blown compressors, height sensors just levered hinges and contacts...not usually the pirmary culprit for major failures....

NTH

Sounds like you have an air leak within the system i.e. airbags, air lines, connectors, etc. Whomever replaced the airbags may have boogered up the plastic connectors. From your pic and descriptions, I think you are riding on the bump-stops as reason for the harsh bumpy ride. The airbags are no longer holding up the truck. The body is resting on the rear axle- see pic.
To answer your questions:
1. The air compressor will only run when you start the truck if air has leaked out or if it senses a heavy load which weighed down the rear beyond its Normal height.
2. Compressor should not run when the truck is off. It will run after you start the engine to correct the height.
3. If there’s a big enough leak, I don’t think the compressor knows to stop. It may continue to run until the compressor burns itself out.
4. The system has 3 fuses and 1 relay. The relay is under the hood in the small black compartment to the left (if you’re facing the engine from front bumper) of the large fuse box.
5. By now, all GX470s are getting up there in age. Though an extremely reliable system, your problem could be the bags, the lines, the connectors, sensors, compressor or air tank. Anything is possible…

Qwertym3

Thank you for your replies. The information you provided are very helpful to me. I will post updates or share information that may help others as well.

Qwertym3

Yes, the bump stops are resting on the axle. Thank you for sharing this. I have no idea. I am posting the image below so that noobs like me will also know.


The height sensors looks fine but I noticed that there are modifications to the frame and the sensors springs were stretched out. I ordered new pairs of sensors. I hope they fix the issue.

Lexus4321

Clean out the air control box, and replace the bags with Arnott bags.

Lines should still be ok.

Qwertym3

Just adding some images on where the air suspension relay is located. I ordered this part since the existing one seems tampered (some loose strands of wire inside and cracked cover).

Qwertym3

Thank you for your suggestions. What do you mean by the air control box? Do you mean the air compressor tank and solenoid valves? Would you know if there is a blog or youtube tutorial for it? Thanks!

Qwertym3

I replaced the relay switch this morning and it did not resolve my non-functioning air suspension. The height sensors I ordered have not arrived yet. Below are some observations after I changed the relay switch:

- After removing the relay, I started the car and the OFF light was blinking. Of course the height switch was no longer working.
- After attaching the replacement relay, the OFF light was no longer blinking and the height switch was working. The air compressor turned on but the bags did not inflate after pressing H. The H led blinked and stopped after a while (light was green on H)
- After running the car around the block I exceeded the speed for H setting and the N led began blinking then stabilized after a while.
- I stopped the car and tried pressing the H control again. This time the compressor did not turn on. The same happens when I press L. Could this mean that the ECU detected faulty height sensors and made the height control switch stop working?

NTH

If you can hear the compressor kicking on but the bags aren’t inflating, it’s probably your bags and not the sensors.
When you press L and nothing happens, this is because your bump stops were already resting on the axle.

ALAN553

99% of the time it’s a leak in the air bags, if the system runs long enough trying to fill them, you will burn out the compressor too. That’s the history of this system and hundreds of threads on this forum. The truck is anywhere from 12-17 years old, the airbags are rubber, they have an end life.

cssnms

The air line from the reservoir height control solenoid valve to the air bag keeps blowing a hole in it which causes my air bag to deflate. The new replacement lasted only a couple of days.

Has anyone experienced similar and if so what caused only one side to blow out? I'd think if it was blowing out from being over pressurized the air line from the compressor or the left air bag line would also blow out. This happened in the same spot on the same line.

My mechanic buddy is stumped.

Davenlei

iTrader: (1)

Is the hole in the same spot in both of the air lines which blew? Is the line rubbing against something? when the suspension articulates, is the line in the way and getting pinched, etc? I have never heard of the nylon air lines blowing. This is a first.