As with all types of air suspensions, the Hummer H2 rear air ride comes with some issues that will develop over time, especially without proper care and maintenance. Your first action should be to diagnose your specific issue, and determine the source of the failure.
The most common indicator of a failing air suspension is a lowered rear end, where the air springs have lost air and have deflated, sometimes even to the bump stops. Turning on your ignition and closing all the doors, including the rear hatch, should activate the air suspension compressor located behind the center of the rear axle. If you do not hear it start up, or your air springs do not inflate at all, you commonly have an air suspension compressor issue.
If your air springs inflate, you may have a leak or a sensor issue. The best way to check for a leak in the air spring itself is to raise the vehicle to the Extended Ride Height, using the ERH button on the dash, which should raise your Hummer two to three inches higher than the standard ride height. This will extend the air springs as well, and with a spray bottle of soapy water you can spray them down and check for any bubbling. Take notice if you see any dry rotting or cracks, as this indicates heavy wear on the air springs and they need to be replaced.
If your air spring do not inflate, you could have an issue with your air suspension compressor. The Hummer H2 series used three different compressors, a single assembly for the 2003 to 2004 models years, and different part numbered dual compressor assemblies for the 2005 to 2007 and 2008 to 2009 model years. The single stage compressor is no longer available as a OE replacement, and can be very hard to find. Hummer recommends you upgrade to the newer dual stage compressor.
A quick and easy test of the air compressor is to use the rear air pump to try and fill a tire. Your Hummer must be running for the rear air pump to turn on, as the rear air pump works off the air suspension compressor and should be able to fill even a bicycle tire with ease. If the compressor shuts off after just a few seconds, or struggles to fill the tire, you may have a clogged inlet line, or even a worn, burnt out compressor. Under the driver’s side rear fender well is the air suspension compressor inlet filter, which could be a cloth or ceramic style. Check and replace this inlet filter if it looks aged or clogged, especially after a few years of use.
Another common failure point for the Hummer H2 air suspension is the Electronically Controlled Air Suspension Relay, located at the steering column right before the firewall, under the Master Cylinder. This relay should be mounted to the frame rail, but it can be hanging loose at times. The symptoms of a blown relay will be the air suspension compressor continuing to run for a period of time after the H2 has been shut off, and a temporary fix is to remove the VSES / ECAS 60 amp fuse located in the under hood fuse block, shutting off the compressor completely until you can purchase a new relay.
A less common point of failure on the H2’s air ride suspension is the leveling sensors, with one located behind the tire of each wheel well, connected to the frame rails. After locating each sensor, turn your vehicle on and manually raise and lower the sensors one by one. These should read as changes in the vehicle’s height, and you should hear the air compressor turn on and fill the air springs accordingly.
Converting your Hummer’s air ride suspension to coil springs can be cost effective, and will provide a stiffer, yet still comfortable ride. By simply removing your air springs and replacing them with coil springs you can enjoy your H2 without the hassles of the faulty air suspension. When purchasing any coil spring conversion kit, always be sure insulators are included, keeping you coil springs from rubbing on the metal frame.
When converting your air suspension to a passive coil spring suspension, you have two alternatives for disabling the warning light on the dash. If all the electrical components and the compressor are still functioning properly, you can dead head the compressor, by cutting the air line running to the driver side air spring and plugging it into the passenger side compressor fitting, fooling the suspension. Your second option is to disconnect the battery and remove the ECAS relay and the Air Suspension Control Module, located on the compressor, before reconnecting the battery, to eliminate the dash warning light.