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

DTCCountHighByte, DTCCountLowByte 
A count of the number of DTCs that match the DTCStatusMask included in a sendOnChangeDTCCount 
request message. 
8.18.4 Supported Negative Response Codes (RC_). 
The following negative response codes shall be 
implemented for this service. The circumstances under which each response code would occur are 
documented in Table 182. 
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Table 182: Supported Negative Response Codes 
Hex 
Description 
Cvt 
Mnemonic 
12 
SubFunctionNotSupported-InvalidFormat 
This code is returned if the request message length is incorrect. 
This code is also returned if the requested sub-function is not locally supported. 
M 
SFNS-IF 
31 
RequestOutOfRange 
This response code is returned if the DTC and FaultType combination 
requested with sub-function $80 is not supported by the ECU. 
M
1
ROOR 
78 
RequestCorrectlyReceived-ResponsePending 
This code may be returned if DTC information is being written at the time of the 
request (depending on memory architecture). 
The ECU cannot process the request message and send the first (or only) 
UUDT positive response within the P2
C
timing requirements. 
C 
RCR-RP 
Where: 
M
1
= Mandatory if sub-function $80 is supported. 
8.18.5 Message Flow Examples - ReadDiagnosticInformation. 
The examples below illustrate the operation 
of each sub-function parameter of service $A9 ReadDiagnosticInformation. The following is assumed for all of 
the examples: 

CAN Identifiers for the ECM (node #1) are $241 (USDT Req) and $541 (UUDT Resp). 

CAN Identifiers for the TCM (node #2) are $243 (USDT Req) and $543 (UUDT Resp). 

The ECM and TCM are the only ECUs connected to the theoretical GMLAN sub-network over which the 
following messaging examples are conducted.