On December 7, 2012 the Office of Defects Investigation (ODI) opened a Preliminary Evaluation (PE) on 2008 Model Year (MY) Road Rescue EV Ambulances. The PE was opened to determine whether a loss of emergency power and accessories to the patient cab area creates an unreasonable risk to patients or emergency personnel.By letter dated May 17, 2013, Wheeled Coach Industries, Inc. notified ODI that it had initiated a safety recall (NHTSA Recall No. 13V-213) to address a safety defect in the vehicles subject to this investigation.According to Wheeled Coach, a failure of the master power disconnect switch can occur, which terminates flow of 12vDC electrical service to the ambulance patient cab.Failure of the programming in the primary multiplex node can affect portions of 12vDC electrical service, including a complete loss of power to the ambulance patient cab.In the event of a failure, the accessory electrical functions such as siren, warning lights and interior patient compartment lights may be intermittent or fail to operate.Wheeled Coach has informed ODI that the chassis function and drivability are not affected.Wheeled Coach's recall action addresses the issues raised by this investigation and, as a result, this investigation is closed.