What is vehicle code 4000A1 VC For California?

Vehicle Code Section 4000a.1 VC makes it "unlawful for the driver of any of the motor vehicles described in sections 24002, 24002.5, 35350, 35400 (except motorcycles two-wheeled vehicles), or 35414, when transporting any persons, or any loads, articles, or objects whatever, to operate the vehicle upon a grade exceeding the posted grade with an unbraked, disconnected, or broken trailer, semitrailer, pole or pipe dolly, auxiliary dolly, logging dolly, sleds, or all other like noncommercial towed equipment except trailers or semitrailers loaded without commercial freight which are so lightly loaded or empty so as not to affect either the steering or driving of the towing motor vehicle".

Basically in other words, this vehicle code means it is against the law to tow any noncommercial trailer, except for unloaded lightweight ones, in excess of what's posted on a downgrade without brakes if it were to become disconnected.