The owner of a 2006-12 Range Rover may come into your store with a complaint that his air suspension system isn't working. He may also comment that a "Suspension Fault" message is displayed on the driver information center.
On likely cause for the trouble, reports Land Rover, is a burnt-up air suspension compressor. The problem seems to affect Hitachi-built units only. Replacing the Hitachi compressor with one built by AMK, part # LR041777, should put the suspension issues to rest. The compressor comes in a kit that includes all the harnesses required to complete the swap.
After the new compressor is installed, Land Rover also recommends replacing the compressor relay, whether it's damaged or not. You'll also have to have the air suspension system reprogrammed to accept the new AMK compressor. Check with a dealer for the application specifics.