rear Air suspension - problem... Please help

[t6chan]

Hello,

First post, would like to say hello and find this forum to have the most technical people relating to Hummers! Hope you guys can help me or at least can help guide me into a solution.

I have an infamous air suspension problem. I got a wiring diagram so perhaps this will be useful to others as well.

We are working with a 04 Hummer H2 with elec. air suspension. The suspension did not react at all. I found that the ground from the suspension ecu was broken, and now I am able to use the inflator only but it?s really weak...

The compressor won?t turn on and all the sensors seem to be in tact.

I wonder how I can test the pressure sensor and if there are any other things to diagnose.

The main relay works and proof is that the inflator initiates the compressor. I haven?t done a bag leak test as I haven?t been able to fill them yet. I will do this tonight by rigging the bags with direct air from my house compressor. (found this from a user who posted it on this forum. - Thanks for that hint!)

Thanks in advance for your help. Haven?t taken it to a dealership, hope to get a look over it myself before paying through the nose. It seems that issues like this can end up costs a ton of dough if the service guy isn?t up to snuff on the air ride suspension.

Cheers,

Tony

[HUMTECH]

If you still have the older single stage compressor setup, there are no serviceable parts on the compressor assembly itself. You can check the air inlet filter, if its plugged output will be weak. Have any codes set. If the compressor is weak you will need to upfit it with the new dual stage compressor assembly. Simple upfit, just need to replace a couple lines and the new assembly bolts right in.

[DrG]

I'm getting a message on my dash that says "Service Air Suspension". Can you guys direct me to some help for that? I'm not getting any codes showing and have noticed the problem occurs more in cold wet weather.

[t6chan]

I was able to get rid of this message by finding a disconnected ecu ground on the compressor frame. This ground is located right in front of the compressor and is bolted on the frame... Could it be a rely that would be sluggish? Just speculating.

On the weekend, i removed the entire compressor apparatus and connected the air bags to a Tee. Now the car is elevated correctly at around 65psi. There doesnt seem to be a leak. i sprayed soapy water and no bubbles.

I determined that there is power going to the unit so the relay up front is good. The inflator in the trunk works okay although seems weak.

Does anyone have any suggesstions on how i can test the valves and pressure sensor with the unit off the truck?

When all together, no messages come up, the compressor will not turn on to fill the bags. The inflator works. The front elevation button light does not turn on nor does anything happen.

Another issue i have is 4x4 switching does not seem to work. The button will blink but it will never switch.

All fuses seem to be okay.

Sorry for the long post but hopefully that gives you enough clues and we can figure something out.

Thanks,

[t6chan]

Another thing if worse comes to worse, has anyone figured out how to remove the Service Air suspension warning? This message is kind of annoying.

Thanks,

[HumminNBoatin']

I have a complete used single stage compressor that I will sell. I does have a leaking exhaust valve. So you would just have to switch your exhaust valve from your current unit to it and then install it.

Odds are you have a good exhaust valve as a bad exhaust valve lets the truck leak down over time.

Does $100 +shipping sound fair?

[IRA51]

http://www.arnottindustries.com/part_HUMMER_Air_Suspension_Parts_yid16.html

[HumminNBoatin']

Yup they want $400 for a unit. Hence why I think my option is a pretty good deal.

[t6chan]

Yeah, that is a really good deal. I have to double check though. I want to make sure that im not leaking in a line or it maybe a short somewhere else.

[HumminNBoatin']

No doubt use soapy water and check for leaks. I thought you said the problems was with the compressor running very weak?
Like it might be seizing up? Sometimes what happens is that the compressor runs to much and the compressor siezes and burns up the motor.