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

2
xx = physical request CAN Identifier. 

$
5
xx = UUDT response CAN Identifier. 

$
6
xx = USDT response CAN Identifier. 
Note:
Emission-related ECUs may use optional OBD CANid assignments. Refer to paragraph 4.4.4.1. 
Example:
Three (nodes) connected to the LS-CAN sub-network (Table 9). 
Table 9: CAN Identifier Assignments Example 
Note 1
 
ECU Diagnostic Address 
(physical node Id) 
PhysicalReqId 
USDTRespId 
UUDTRespId 
$22 
$42 
$11 
$24A 
$243 
$25E 
$64A 
$643 
$65E 
$54A 
$543 
$55E 
Note 1:
PhysicalReqId
= Physical Request CAN Identifier; 
USDTRespId
= USDT Response CAN Identifier; 
UUDTRespId
= UUDT 
Response CAN Identifier 
 
Note:
There is no numerical relationship between the ECU Diagnostic Address and the Diagnostic CAN 
Identifiers. The Diagnostic address shall be unique for every ECU on the vehicle but the diagnostic CAN 
Identifiers are only required to be unique on a given subnet. This means that two devices on different subnets 
may use the same set of Diagnostic CAN Identifiers but their Diagnostic addresses are different. 
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GM WORLDWIDE ENGINEERING STANDARDS 
GMW3110 
© Copyright 2010 General Motors All Rights Reserved 
February 2010 
Page 26 of 336 
4.4.4.1 Optional CAN Identifier Assignments for Emission Related ECUs. 
Table 10 details the usage of 
the 11-bit OBD/EOBD reserved CAN Identifiers. Each GMLAN emission related ECU that supports legislated 
diagnostics (as defined in SAE J1979/ISO 15031-5) with 11-bit CAN Identifiers must support the $7DF 
functional request CANId, one of the eight reserved OBD/EOBD physical request CAN Identifiers, and the 
OBD/EOBD physical response CANId associated with the supported physical request CANId. All of the 
OBD/EOBD CAN Identifiers utilize the USDT protocol and normal addressing. See paragraph 4.5.1.1.1 for 
more information on addressing types.