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

GM WORLDWIDE ENGINEERING STANDARDS 
GMW3110 
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February 2010 
Page 83 of 336 
8.2.8 Tester Implications. 
The disableAllDTCs ($02) and enableDTCsDuringDevCntrl ($03) levels of this 
service require a tester to send the TesterPresent ($3E) service at least once every P3
C
ms or the requested 
functionality will be terminated. 
 
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GM WORLDWIDE ENGINEERING STANDARDS 
GMW3110 
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February 2010 
Page 84 of 336 
8.3 ReadFailureRecordData ($12) Service. 
This service is used to obtain failure record information that was 
captured due to a fault detected within the node.
 
8.3.1 Service Description. 
Two levels are used within this service to be able to obtain the failure record 
information from a node. One level, readFailureRecordIdentifiers (sub-function parameter = $01)
,
allows the 
tester to obtain information necessary to send a request to retrieve the data parameters associated with a 
specific failure record stored in a node. The information needed to request specific failure record data is called 
a failure record identifier and is comprised of a failure record number and the DTC identifier (2-byte DTC 
number + 1-byte DTC fault type). The second level, readFailureRecordParameters (sub-function parameter = 
$02)
, 
allows the test tool to retrieve the data parameters in the failure record associated with the failure record 
identifier. 
Note:
Refer to the $A9 service and Appendix E for more information. 
Note:
In emission-related devices, failure record number $00 is also known as the Freeze Frame and shall be 
reserved for Emission Related Freeze Frame data required for OBD and EOBD. The Freeze Frame is required 
for storing the failure information for the first emission related DTC that is stored. There are certain specified 
data parameters that are required to be captured in the freeze frame for OBD and EOBD. The required 
parameters for OBD are documented in SAE J1979 and for EOBD are documented in ISO/WD 15031-5. 
Additional data parameters may also be captured and stored in the freeze frame if they are needed for 
engineering or service. 
Data parameters that are stored in a failure record must be identified by the node with either 2-byte Parameter 
Identifiers (PID) or 1-byte Data Packet Identifiers (DPID). The node will indicate which format is used with the 
failureRecordDataStructureIdentifier parameter in the readFailureRecordIdentifiers positive response. A 
failureRecordDataStructureIdentifier parameter value of $00 indicates that PIDs are used to identify the data 
parameters in the failure record. A failureRecordDataStructureIdentifier parameter value of $01 indicates that 
DPIDs are used to identify the data parameters in the failure record. 
All failure records for a given node shall support the same format. PID and DPID numbers and their associated 
data shall be coordinated with service and manufacturing and shall be documented within the device
’s CTS or 
within a supplemental diagnostic specification referenced by the CTS. 
Note:
Nodes that support failure records shall clear all association of failure record numbers to DTC numbers 
upon a successful code clear.