Are they helper (in addition to the leaf springs) bags or a totally custom system?
If you have a wireless remote for the system it's probably the 3volt waffer battery inside the fob. They usually have a small notch in the side somewhere to pry it open. Some also have small screws that hold the cover on. Then you should see the battery inside. If you check The battery with the voltmeter anything below 3 volts is shot.