The purpose of this SAE Information Report is to specify the requirements necessary to fully define the Serial Data Communication Interface (SCI) used in the reprogramming of emission-related powertrain Electronic Control Units (ECU) in Fiat Chrysler Automobiles (FCA) vehicles. It is intended to satisfy new regulations proposed by the federal U.S. Environmental Protection Agency (EPA) and California Air Resource Board (CARB) regulatory agencies regarding "pass-thru programming" of all On-Board Diagnostic (OBD) compliant emission-related powertrain devices. These requirements are necessary to provide independent automotive service organizations and after-market scan tool suppliers the ability to reprogram emission-related powertrain ECUs for all manufacturers of automotive vehicles. Specifically, this document details the SCI physical layer and SCI data link layer requirements necessary to establish communications between a diagnostic tester and an ECU. It further specifies additional requirements for the application of a flash strobe voltage multiplexed on the SCI communication link for purposes of ECU reprogramming. This document does not specify the content or meaning of the application messages or diagnostic protocol to be transmitted on the SCI communication link. It only defines a generic method to transfer data between a diagnostic tester and an ECU, regardless of application messaging structure. This document has been written defining the SCI communication link from the Tester's point of view. This specification will be referenced from within SAE J2534-1 Pass-Thru Programming as a technical information report. In this regard, the inclusion of the SCI communication link is in addition to the approved OBD communication links previously specified in SAE J2534-1, and constitutes unique Fiat Chrysler Automobiles (FCA) manufacturer-specific requirements.