Service Air Suspension...Again!!! HUMTECH

[HUMTECH]

If the compressor is running it is trying to inflate the bags so calibration is not an issue. Is there air going to the other line? if not i would say your compressor is hooped. I dont know the part numbers but any gm dealer should be able to find them, there should be a note in there catalogue for required parts when upfitting the dual stage compressor in place of the single stage unit

[14u2nv2]

I haven't checked the other (passenger side)line, but there is some pressure in the air spring, although that side isn't raising either. The driver's side air spring was completely empty before I removed it and had no pressure. I'll check the other(passenger side) line tomorrow.

Can you tell from the photo if this is the newer two-stage compressor or the older single stage...





Thanks again,

John

[Planohummer]

that's the original single stage.
the amount of pressure for lifting the truck is a whole lot more than what's at the rear aux port. This may be why the pump runs ok when it's not lifting the truck.
You really need to check the DTCs before you spend any money-make sure it's not just a height sensor recal issue or something similar. Any GM store can ck the codes for you, when you get them post them on the forum and we'll decipher.

[jarek m]

Believe it or not I had the same thing happened today:

Symptoms
- service air suspension light
- compressor runs for 20 seconds at start up
- rear end does not come up
- passenger slightly inflated
- driver side empty
- no air coming from driver side line

Already checked
- inflation system goes to well over 100psi
- driver side air bag has no leaks
- both sensors have been recently replaced
- air compressor has been changed year ago
- disconnected the battery for a while with no effect
- raised the body and cycled the compressor without driver inflating or passenger changing air pressure


Mine happened after towing my other SUV for couple hundred miles. Also ever since two years ago I changed one of the air bags then in little while each of the sensors then the compressor I never reset the system, my dealer claims there is no such a procedure!!!(Gold Coast Hummer Dealer)

[HUMTECH]

Well the procedure is lift the rear of the truck, and install the calibration blocks between the bump stop and diff housing (every Hummer dealer should have these as an essential tool) depressurize the air suspension system. With the tech 2 go to chassis, air suspension, special functions and then trim height learn. If everthing is good trim height learned will be displayed. raise the rear off the calibration blocks and remove them. close all doors, run truck and verify system works.

[HUMTECH]

And yes Plano is correct, it should be scanned to be sure prior to forking over a pile of money on parts

[jarek m]

Originally Posted by HUMTECH

And yes Plano is correct, it should be scanned to be sure prior to forking over a pile of money on parts

Thanx HUMTECH!