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

USDT-CF
USDT-FC
USDT-FC
ECU #1 Transmit
Tester Transmit
Tester NWL
P2
CT
P2CT*
0
P2CT*
P2
CT
0
P2
CT
150
0
req
con
150
0
P2
CT
ind
ind
ind
ind
Tester internal status:
RC78PendingEcuCounter
RC78PendingEcuList
P2CTReloadValue
+1=1
ECU#1
5100
no change
no change
no change
-1=0
ECU#1
150
0
150
no change
no change
no change
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GM WORLDWIDE ENGINEERING STANDARDS 
GMW3110 
© Copyright 2010 General Motors All Rights Reserved 
February 2010 
Page 58 of 336 
Figure 27: Tester P2
CT
* Timing Parameter Definition - Multiple ECUs Responding 
In Figure 27, the tester transmits a functionally addressed request message and three ECUs respond. Two 
ECUs request enhanced response timing and one ECU immediately responds with a multi-frame response 
message (two consecutive frames). Based on the general handling of P2
CT
the tester has to restart the P2
CT
timer with each starting response message provided the response is associated with the request message. At 
the point in time when the tester receives the first negative response with response code $78 the tester 
modifies the reload value of P2