What were the enforcement procedures for “grandfathered” AOBRDs and ELDs during the two-year period following the compliance date of the ELD rule?

During the period when both “grandfathered” AOBRDs and ELDs were allowed (December 18, 2017 to December 16, 2019), authorized safety officials enforced ELD rule requirements for ELDs and the requirements in 49 CFR 395.15 for “grandfathered” AOBRDs. The supporting document requirements for drivers and motor carriers using either device applied on and after the ELD rule compliance date of December 18, 2017.