Hey guys, I have an air suspension issue I would like to sort out on my 2003 single compressor H2. Two things happen, one is when it is parked the back will droop down a couple inches each day the vehicle is not started. The other thing that happens is the hummer is fired up and the air suspension fills back up and stops at the correct height. Then after a few seconds you hear a click and it lets air out and go's down an inch or so and then the compressor kicks back in and lifts it back up. I may do this a few times in a row and quit for a while or sometimes continually. I replaced the airbags as they were getting those small cracks at the fold. That didn't fix it. I sprayed the air line connections with soapy water and I noticed some bubbles coming out of the cover plate of the manifold (i think that is what it is called). It's the component that leaves the compressor and directs air to the dryer, inflator, and exhaust vent. Pulled the cover off and the solenoid out and there was a tiny bit of corrosion in the case, cleaned that up and regreased the o-ring on the solenoid. RTV'ed the cover and put it back together. Still doing the same thing.

I assume the click i hear is that solenoid opening letting the air out until the Hummer droops and the level sensors tell the compressor to kick back on and level the SUV. Do you think the control module is bad or is another sensor telling it to deflate the bags like the level sensors or pressure sensor?

 

Thats what mine was doing and it wasnt the bags also. I found 1 leak with the new bags where the line came in by spaying soapy water, then I also found that the solenoid valve(aluminum block) that both the bags run to was leaking from the internal orings where the lines connect. I replaced them and that solve my air leaks. I also replaced my airlines with some cheap ebay airlines.

after it fills up its normal for it to click and close the 2 solenoids on the valve(aluminum block) and then release the air between the compressor and the valve.

 

How do those fittings remove? Do you have to remove the solenoid?

 

For the ealier compressors there is a software update that makes them act better. You would need a dealership to install the update or your own Tech2 (or other device with Tech2Win and access to the updates) with TIS2000. I did the update on my 03 and it did calm it down so that it did not do so much up down stuff just after starting up. Sounds like you did get the leaks sorted out though which is good.

Hum Dinger - to release air lines you press the little ring collar in around the fitting and then just pull the air line out. That being said they do not always come out easily as the o-rings in the fittings are probably somewhat hardened and stuck to the air lines from age and there is a good chance you will create leaks. The air line where it was in the fitting might also be somewhat compressed from age so you might also need to cut a half an inch off the end of the line. If you are inclined, after removing lines, on many fittings you can carefully pry the locking collar out and replace the o-rings in the fitting as well but finding the exact right size o-rings is on you.... I've done this by taking o-rings from new cheap fittings from Amazon before and they did work.

 

Kinda restating the above, once you get the lines out of the parts circled in red, i just used a small screwdriver to gently pop them out. Once they are out there are 2 orings on each side that you pull out with a pick.
I think the correct size for the oring is 6mm in/10mm out and try to match up the thickness, I ended up using a 5/10 cause the 6/10 was still leaking. I think I bought about 6 different sets from Ace Hardware to try. The air lines for the air springs are 6mm.
In order to see if those are leaking you can get to the valve while in place by removing the rear bumper and taking off the air dryer. depending on how flexible and coordinated you are you can remove the valve completely without dropping the whole assembly, I did that a few times to find the best size orings and it was way easier than trying to drop it down plus you can get to all the airlines easier if you still want to drop it down. If your going to mess with it, remove the rear bumper, its just 6 bolts(2 behind the tow rings) and its connected to the rear fender liners, hardest part removing that it unplugging the trailer electrical plug from the backside

 

Ok. Bought a Tech 2 to help with this and another issue. I can’t seem to get the Tech2 to do the air suspension height calibration. It is communicating with the air module as I am getting data and can turn the compressor on and off. It will not do anything when I try to deflate the system or learn the ride height. I click the on button and nothing happens.

I upgraded the software for the air module and that didn’t help. The ignition is on, door closed, extra accessories that draw power are off, battery charger on to keep battery above 12 volts, cigarette lighter power plugged into cable, jacks under chassis to hold it at my desired height.

any ideas?

 

try changing the date on the tech2 settings page somewhere in the early 2000's instead of current date. it can cause a rtc failure on boot up. maybe that has something to do with it

 

I was wondering what that RTC fail was. I will give it a try. Not holding my breath because I have updated almost all devices on the truck without issue.

 

QUOTE=HUM DINGER;401507]I was wondering what that RTC fail was. I will give it a try. Not holding my breath because I have updated almost all devices on the truck without issue.[/QUOTE]
I too had the "RAM Fail message" and after replacing the RTC chip and crystal found out it was a software issue. I somehow fixed it by going into "F4 Tool Options" -> "F0: Set Clock" and played with the date settings, seem to recall setting the date to something like 2016, rebooted without the error, then reset the RTC to the current date. Now the date on my Tech2 is now fine i.e. "June, Monday 26 2023 1433" with no RTC Error.

Also found the Tech2 works better with just the ODB2 port connector and no 12V adapter as it gave an extra ground loop which affected comms.


These are the GM service manual instructions (note CH-47816 are the calibration blocks which few of us have)


Important: Before proceeding with the steps below, ensure:

• There are no stored diagnostic trouble codes stored in the ASCM.
• The vehicle is on level ground.
• There are no occupants in the vehicle.
• The tire pressures are at the recommended kPa/psi.
• All vehicle doors are closed.

Raise the vehicle on a hoist.
Install the CH-47816 on to the LR and RR jounce bumper mounting cups.
Lower the vehicle off the hoist.
Depressurize the air suspension system in order to allow the full rear weight of the vehicle to rest on the blocks and rear axle. Refer to Air Suspension Depressurization .
Turn ON the ignition, with the engine OFF.
Install a scan tool.
With the scan tool select Chassis.
Select Air Suspension.
Select Special Functions.
Select Trim Height Calibration and press the Enter key. The scan tool will flash Calibration In Progress, then display Calibration Complete.
Press the Exit key.
Pressurize the air suspension system until the rear weight of the vehicle is lifted of the blocks. Refer to Air Suspension Pressurization .
Remove the CH-47816 .
Ensure all vehicle doors are closed. Cycle the ignition switch OFF then start and run the engine for 2 minutes to allow the vehicle to level at the designed ride height.
After ensuring all vehicles doors are closed, use the scan tool to raise and lower the vehicle by commanding the extended ride height switch special function each time to verify the air suspension system is functioning properly.

 

Thanks Bronx and Ocean, changing the date did fix RTC fail. I haven’t had a chance to try the level learn again.
The only thing I didn’t do in the test procedure was have the vehicle on level ground. My driveway has a slight slope to it. I’m not sure why that would affect it unless the H2 has some sort of inclination sensor in it. I will also try it without the extra power connected to the cable.