The symptoms I'm getting are with the rear, front is fine. The back shocks drop like there's no air. If I switch the control to "high" nothing happens but if I drive it for about 10 miles they will raise up and stay good for a while, sometimes 1 day, sometimes 2 or more. I can't hear if the compressor is working b/c I have a very loud noise coming from a servo motor on the heater assembly. No codes come up when I check it. I've never worked on this system before and I don't have my manual. Question is, what and how do I check? Any input is appreciated.

 

I figure it's a loose electrical connection somewhere b/c it's intermitent. I can turn on the compressor from the ECU so I know that's good but it still wont pump up the rear shocks. I need to check more when I get a shot but from what I've read elsewhere it might be the connection on the alternator. (Of course the PS fluid is leaking on it) Everything is starting to go wrong at the same time with this car.

 

Well,.......it has done it again. I went out this morning and the rear was dropped to the ground. It's been fine all week so I didn't think about it. But now I'm almost convinced the rear height sensors are effected by the heat somehow. It was 98 and very humid yesterday, same as when it happened last week. Has there been any common problems with these sensors, over the years or maybe condensation in the air lines?

 

Next time the rear is inflated just turn the system off in the trunk. This should disable the valves so if it is due to a short of some sort it should stay inflated.

 

Thanks for the idea, I'll give that a shot. Anyone ever ride with the air ECU unhooked? Just wondering how the ride feels w/o it adjusting itself. Will that do anything to the shocks themselves, not letting the air release from the relief valve? I just dont want to blow a shock and have myself some more problems.

 

I think there may be some connection between temperature and ride height sensors when they begin to wear out. I haven't quite figured out a specific pattern yet, but I do have some intermittent rear sensor problems that are scheduled to be resolved by replacement. Occasionally the sensor will cause the suspension to fully inflate and ride stiff....other times it rides perfectly. Mine likes warm better than cold it seems.

 

I can't believe it, a year went by with it working pretty much normal.
Now, its acting up again. I never fixed anything on it b/c it was working. For a while now (8-9 months) if the car sits about 10 hrs the rear lets out more air then the front. But it always pumped up to normal when I started the car. The past couple days the compressor hasn't come on. I haven't checked anything yet due to a work injury. (Rotator cuff, right shoulder) But I am more convinced the problem IS due to the heat and the height sensor. It has been very hot and
humid the past couple weeks.
Just figured I would give an update incase anyone searches for the same problem in the future.

 

I know a Japanese guy who has experienced a similar problem with you. But his problem was at the front side only. Both driver and passenger side of air suspensions were too low time to time. But the rear was always OK.

To make a long story short, it was caused by an O-ring used at the height control valve for the front. There are 2 different valves for the front and the rear. The O-ring of his 98 Celsior had a minor scratch and it caused the problem intermittently.

Those two are controlled by the ECU for the air suspension. Other than those two, there are "suspension control actuators" that are also controlled by that ECU but those are related only for a single suspension.

Since you have the problem for rear two suspensions and I assume that the height control valve for the rear has some problem.

 

makes sense that the orings are failing when the weather is getting hotter and more humid. this is typical of our stock air suspension being over 10 years old. as for the compressor not turning on, it could be as simple as a fuse. good luck!

 

I'll check the O-rings out when my shoulder is better and as for the compressor, it works now. Something intermitent with the electrical. I can't figure it out. Oh well, one of these days maybe.