Like what was mentioned earlier. The cab leveling valve is tied into the CTIS and also the engine fan. When I went to the maintenence class this was pointed out. The pins are only used for air transportation only, in conjunction with the front suspension pull down cylinders and the kneeling valves on the front tires. Kneeling valves connect to the Schrader valves going into the tire, it has a flat tip like look to if. You may not have them anymore as the ARMY now changes out entire wheel Assy. If you don't change them out they disappear. One more thing about the air bags, if one goes bad and you can only get the other side assy, just unbolt the bag from new and use old mount. If this stuff has already been brought, my apologies since it's been quite awhile since I've been here.