OVERVIEW
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This document describes DaimlerChrysler Corporation's proprietary Serial Communication Interface (SCI) Diagnostic Protocol pertaining to 2001MY Powertrain Control Module (PCM) applications. The SCI diagnostic protocol is an internal proprietary 'byte-based' protocol that defines the necessary diagnostic test modes required for engineering, manufacturing, and service. The diagnostic protocol specifies the diagnostic services, data content, and command format required for data exchange between off-board peripheral test devices and on-board powertrain control modules. The SCI protocol supports multiple baud rates to accommodate the low-speed diagnostic command mode (at 7812.5bps), the high-speed data parameter interrogation command mode (at 62.5Kbps), and the high-speed flash reprogramming command mode (at 62.5Kbps or 125Kbps). Most data is transmitted at the low-speed baud rate of 7812.5bps for diagnostic test support.
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For all gasoline engine applications, SCI is used for flash reprogramming, engineering development/system calibration, and enhanced diagnostics. For most transmission applications, SCI is used for flash reprogramming and engineering development/system calibration only (other means are used to support enhanced diagnostics). Also, SCI has been adopted as the standard communication interface and diagnostic protocol for all Cummins diesel engine controller applications. Specifically, this document contains information regarding SCI implementation for the engine control module and transmission control module applications as shown below (note the diesel engine control module applications are listed but not covered in their entirety):
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