General Specification Electrical Function gmw3110 General Motors Local Area Network Enhanced Diagnostic Test Mode Specification

GM WORLDWIDE ENGINEERING STANDARDS 
GMW3110 
© Copyright 2010 General Motors All Rights Reserved 
February 2010 
Page 249 of 336 
proliferation of tool programming software to a minimum. A utility file is broken into 3 distinct sections; the 
Header Information section, the Interpreter Instruction section, and a Routine section. The Header Information 
section contains data that is typically constant during a programming event (e.g., the interpreter type which 
defines the communications protocol used for programming). The Instruction section contains the Operation 
Codes (op-codes) used by the programming tool to step through the programming event. The Routine section 
contains ECU specific programming routines or programming algorithms (e.g., flash erase and write routines). 
The Header Information section of the utility file includes data which defines the interpreter type. For GMLAN 
controllers, the interpreter type indicates that the ECU resides on a GMLAN CAN protocol link (as opposed to 
a Class 2 or KWP2000 link). The utility file does not contain any information which tells the programming tool 
which GMLAN subnet the ECU resides on. The programming tool must determine subnet location of 
programmable ECUs in the steps prior to the execution of a utility file. Refer to paragraph 9.4.1 for further 
details on how the programming tool determines which subnet the ECU resides on. 
The utility file does not contain ECU CANId information. The op-codes within the Interpreter instruction section 
contain action fields which include the diagnostic address of a GMLAN ECU. Using the diagnostic address 
within the utility file (instead of the CANId) allows a single utility file to be used on the same ECU across 
multiple platforms where the CAN Identifiers could not be standardized. The identification of CAN Identifiers 
assigned to the target ECU(s) must be determined in the steps prior to the execution of a utility file. Refer to 
paragraph 9.4.1 for further details on how the programming tool correlates the diagnostic address to the 
appropriate request and response diagnostic CAN Identifiers. 
All diagnostic services executed via utility file instructions shall be physically addressed to the ECU to be 
programmed to allow for parallel programming. See paragraph 9.4 for more details.