How to diagnose rear air suspension?

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ukrkoz

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Hi all
Brand new 2011 QX owner.
Bought it several hrs ago and, lo and behold, got home and was pointed that the rear end is lower than the front.
I got my hand through the wheel spokes and both air bags are deflated. Also, I do not hear compressor buzz, when I turn system on.
Here's my question:
How do I trip compressor into action? I have car lift, I can get to it easily. Obviously, need to check if it works. Same time, I'll check if bags were torn, of course.
Otherwise, truck drives very nicely, just a bit, little bit, bumpy in the rear. I had same issue with my Tahoe, first, bags were torn and then comp died, had all replaced, no big deal.
But I want to start with comp.
Thank you

Compressor does NOT turn on, when I start the car. Fuse in fuse box 1, large one, is good. I am not sure, if there is another one somewhere.

And now I have another question. Do I have air ride or hydraulic ride? How do I find out?

How applicable is this to QX56?

 
open the hatch, sit 3-4 human sized people on the rear hatch. for a 3-4 minutes. confirm rear is sagging with weight of people on it. turn on car. in about a minute or less you should hear the compressor kick in.
 
Thank you but I clearly see that rear is sagging. Also, air bags are deflated.
Also, I do not have spare humans to sit in the hatch.
Anyone knows how to jump compressor? I simply need to know, if it's comp or levelling sensor, or fuse, or relay.
 
you can use any kind of weight - anything that weighs down the rear.

just because rear is sagging does not mean the compressor does not work. the auto leveling sensor may be faulty.

the ipdm relay box in the engine room has relays there you should check.

as for the hbmc, you can call an infiniti service depot, give them your vin and they can tell you.

the compressor system is the same as what is on an armada so you can search youtube for the armada leveling system as well.
______________________________
 
All right. I have weights, I lift for 40 years. So the point is to trip the leveling sensor, right?
I'll get her up on the lift and rummage there. I'm PRAYING for bags not to be torn as mine does have hydraulic levelling and it's very spendy to replace them. Plus, system has to be refilled and bled and it's not a DIY job.

What's ipdm and hbmc?
 
Ok, I have C1 803 EXH SOLENOID error code in suspension compressor section module.
Is that solenoid a separate unit or it it is integrated into the pump?

Bad compressor.
Replaced today and it all works fine.
 
Reviving the thread:

I am reviving the thread.
All was good for over a year.
Rear airbags stayed inflated as they should.
Last Saturday, I installed Firestone in spring air bags. Made sure not to damage anything along the installation.
Pumped them up and it all went well.
Yesterday, I noticed that rear is lower than front. Measured, indeed, was about half inch lower.
This is what I found:
1. one Firestone airbag is slow leaking air at the air line connector. Between the brass connector and bag itself, not from the air line to connector.
2. OEM air bags are completely deflated.
I put system in Aux mode and waited. Compressor will not come up.
I connected scanner and went into functions. Found Compressor in E-SUS section and it started from scanner without problem.
Apparently, compressor works fine.
Height sensors were replaced during the original post, 1.5 year back.
What can prevent compressor from kicking in then?
Problem is, until I receive replacement Firestone air bag, I either have to let rear to sag completely or, pump Firestone bags every day, pretty much.
Could it be caused by Firestone bags not allowing vehicle to lower itself enough for the sensor to trip compressor?
It drives much better with both OEM and Firestone bags inflated.
 
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