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

B2.3 Learned Source ID Reset. 
Implementation of this device control allows a tool user to force the ECU 
relearn of all previously learned Source IDs. This is accomplished by resetting the learned Source IDs as 
follows: 

Required messages that are always guaranteed to be present in the system shall be associated with 
Source ID $FF. 

Optional messages whose presence is determined by the presence of a build option shall be associated 
with Source ID $FE. 
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GMW3110 
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The module
’s handler shall relearn Source IDs for any message that contains supervised signals each time the 
message is received. Only the most recently received Source ID shall be associated with each message that 
contains supervised signals. Support of this device control allows ECU swapping between vehicles. Otherwise, 
ECU swapping can only occur when all build options are identical between the two vehicles or false Lost 
Communication DTCs will occur. If this device control is used when an ECU is not communicating (valid Lost 
Communication DTC), the bus speed specific CAN Communication Bus Performance DTC will set rather than 
the ECU-specific Lost Communication DTC. 
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February 2010 
Page 296 of 336 
Appendix C: Corporate Standard Data Identifiers (DIDs) 
This Appendix contains a list of all corporate standard DIDs. Corporate standard DID numbers shall occupy the 
range from $80 to $FE (application specific DIDs shall use the range of numbers from $01 to $7F).
The use of DIDs provides a mechanism for tools to access predefined data within an ECU without having to 
know the actual ECU memory address where the data is stored. DIDs can be read only, or have read and write 
access. The $1A service is used to read DID information and the $3B service is used for writing DID 
information into an ECU. It is recommended that a tester use physical addressing when requesting a DID 
which results in a multiple frame response message, unless the tester can send the flow control frame(s) to 
each responding ECU before a network layer timeout occurs.
The tables below are structured to provide a user the needed information to correctly implement a corporate 
standard DID that is applicable to a specific project. Which corporate standard DIDs apply to a given project 
must be agreed upon by the Release Engineer and representatives from Service Operations and 
Manufacturing (e.g., DVT and In Process Tester Development Engineers). The columns within the tables 
contain the following information: 

The hex representation of the DID value. 

A description of each data parameter for a given DID. 

Whether the DID can be read (R), written (W), or both (R/W) in the ECU. 

An * after the (R) or the (W) in the R/W field indicates that SPS security is required for reading (R*), writing 
(W*), or both (R*/W*). Reference the global pseudo code variable Security_Access_Unlocked set to a 
value of TRUE in paragraph 8.8.6.2. 

The format of the data for a given DID (ASCII = American Standard Code for Information Interchange, 
BCD = Binary Coded Decimal, USN = Unsigned Numeric, BIN = Binary or bit encoded). 

The byte length (Len) of the parameter data.