I had a Fabtech 6" lift that retains the factory air bag system installed and ever since I have had a problem with the compressor coming on.
When I turn the key, the compressor cycles and stops. The light on the dash button flashes showing its working but the truck does not self level and pushing he dash button doies nothing. The light does not start flashing and the compressor does not come on. The problem is intermittent.
On a few occasions I have been able to wiggle the main connector to the harness mounted to side of the compressor and it comes on, works for awhile, then stops. Then cant do it again. I have taken apart that connector, cleaned it, dielectric grease, etc.

Its acting as if it thinks a door is open. All my door switches are operating correctly. No ope door notice on the dash.
The service air system message does not come on.
If I disconnect that main connector and plug it back in, the compressor cycles quick then stops.

The truck needs to have the ride height set and an alignment but I cant do that without the air system working.

Before anyone says ditch the air system, I would like try and fix this. I trailer a lot and like it.
Is there a schematic for that harness that might show me which wires I should pay attention to?

 

So it just came back to life and its not happy. Compressor running it up, letting it down, just keeps cycling up/down.

I wouldnt mind just deleting all the automatic stuff and have a compressor, air bags, and an up down switch. I would even settle for a manual release valve for the down.

 

I have the Stock Air ride on my 09 H2... I had a Problem with one side being higher then the other,, Turns out the low side I thought was the problem. Thinking it was the sensor on the swing arm on that side. As it worked out ..it was the high side bad sensor, It was sending erratic signals to the body computer.

My Mechanic hooked up that 5 bazillion dollar GM tech tool and watched the readings from that sensor, It was freaking out..

Had it changed oy and am good to go.

 

Some of the Chinese Tech 2 devices work perfect and are virtually identical to the official Bosch Tech 2 from GM. I bought mine from here Newest Vetronix Tech2 Diagnostic Scanner Working for GM/SAAB/OPEL/SUZUKI/ISUZU
A whole lot less than a bazillion dollars and has been worth every cent as far as diagnosing and testing things that no other OBDII scanner can deal with. The rear air ride is one specific thing - its has all the tests for that as well as the ability to recalibrate the ride height, etc.

 

Can the sensors be calibrated via a scan tool?
I unhooked the battery last night and set both sensors to give full extension so I know they are as close to the same as possible. The truck self leveled but one side is about 2" higher.

The shop that did the install has been a nightmare so I have taken over the final setup myself. Fabtech has been great about giving me exact ride height measurements from the center of the axles to the bottom of the fender well. I made a nice tool using a level with a T-Square attached to the side to measure up from the center of the wheel cap to the bottom of the fender. Works great, I can post a pic.

 

The only tools that can communicate with the air ride module and perform the calibration and run tests is the GM Tech 2 or a GM MDI (connected to a computer that is running Tech2Win). You will probably have to go to a GM dealer unless you, a mechanic you know, or someone else you happens to have a Tech 2. With the lift I'm not sure if a GM dealer will fuss about calibrating it or not. Another big plus for the Tech 2, is to get one that includes the TIS 2000 software. Then you can also update all of the electronics modules which can fix issues like intermittent seat heaters, air ride issues with the pump cycling too frequently, etc.

 

Thanks, going a different shop tomorrow who has the equipment.

 

My HUMMER Dealer has 10 Hummer Mechanics from when they had a HUMMER dealer ship before GM shut the line down. They no Their stuff. My Guy who always works on my rig hooked up the GM Tech tool and adjusted the settings thru that tool. Rig is now perfect on each side.

My suggestion to you is ...Use a GM dealer with Air Ride Ride no how. I think that system is a standard system used in all Air equipped GM Cars. My Neighbors Caddy Escalade uses the same system.

Just My $.02 worth

 

My truck is in the other shop now and he is finding all kinds of crap.
When the shop installed the lift one of the torsion bar keys bacame unseated from the adjusting bolt. If I understand, the bolt fits into a little pocket in the key. The first shop couldnt figure this out and tried compensating. One bolt was almost all the way in and the other side out. That staill dodnt get it level but close so the screwed with one side of the rear sensors which also effects the front a little.
He said one of the rear sensors was wayyyy out of calibration. He has a TEch II and is working on it now. Ill be taking he bill to the first shop and then probably get arrested. :-)

 

MixManSC's advice is very good, the Tech2 is very useful and worth the minimal investment.

The AS system is very useful despite the occasional issues so I agree with you, worth keeping. However it is VERY sophisticated and would be difficult to replicate any other way. For example the electronics provides:-

• Air-Pressure measurement (PSI)
• Inlet & Exhaust Valve control with individual current measuremt
• Battery Voltage measurement
• Ignition "On" Detection
• Compressor Over-Temperature detection
• Dash Extended Ride-Height Switch and Lamp control (doors must be closed to activate!)
• Left & Right Ride-Height sensor voltage measurement 0-5V, 2.5V = nominal height approx., voltage increasure with ride-height
• Left & Right Ride-Height current measurement
• 5V Supply On/Off control (turns sensors off)
• Tyre Inflator control
• Experience indicates ride-height sensors can be changed without re-calibration.
• EEProm storage of ride height calibration etc.
• Communications to BCU

It sounds like your new shop is doing fine, hope it goes well, keep us posted!!