If a tank vehicle is equipped with vapor recovery kits, grounding and bonding cables, or an emergency shut-off system, what must the driver do before driving?

AAMVA CDL Manual §8.1.2, p.8-8-1

Special-purpose equipment like grounding cables and emergency shut-offs exists specifically to prevent fires and control spills during loading and unloading of flammable or hazardous liquids. Equipment that is present but broken gives a false sense of security, which is why the manual requires drivers to confirm it actually works, not just that it's installed.