Service Air Suspension...Again!!! HUMTECH

[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!

[14u2nv2]

That's good news Jarek.


Planohummer and Humtech,

I'm having it scanned at the Caddillaic dealer tomorrow.

Is there a list of things(codes/procedures) I should have them check while it's on the Tech 2?

Thanks again,

John

[14u2nv2]

Just got back from the dealer.

It's showing a DTC C0711 --Level Control Air Pressure Sensor Circuit code. Cleared it and got the same code again.

The tech wasn't sure what that code means, and thought it needed a ride height calibration, but they didn't have the calibration blocks. I'm no expert, but I don't think that code sounds like a ride height calibration issue.

I have to admit that I was a little bit concerned when they told me that the air spring was broken because it wasn't connected at the bottom mount when they lifted it on the lift. I had to explain that since there was no air pressure in the air spring, it's not expanded. This dealer was a Hummer dealer until about a year ago and is now Cadillac.

Is the pressure sensor on the compressor assembly, maybe in the photo I posted?

Any tips on deciphering this?


Thanks,

John