The air dump valves are electric solenoid controlled, while the height valves are mechanically linked between the axle and the frame. You could find the dump valves by looking for wires going to the solenoid valve that is in the air line to the air springs. If you have the RV run up on blocks to make sure you won't be crushed even if the air springs dump all air, you could go under and have someone operate the dump valve. The escaping air will verify you've found them.
Linear Mode
