Cal. Civ. Code § 2986.6

No agreement in connection with a lease contract which provides for the inclusion of title to or a lien upon any personal or real property, other than the motor vehicle which is the subject matter of the lease contract, or accessories therefor, or special and auxiliary equipment used in connection therewith, as security for the payment of the contract obligations, shall be enforceable. This section does not apply to a security deposit, advance payment of rent or other cash prepayment.