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

GM WORLDWIDE ENGINEERING STANDARDS 
GMW3110 
© Copyright 2010 General Motors All Rights Reserved 
February 2010 
Page 294 of 336 
If a TesterPresent timeout occurs while this device control is active, the device shall terminate this device 
control but no negative response is sent. The device will however send the unsolicited mode $20 response 
message when the timeout occurs. 
B2 CPID $FD 
Table B2: Corporate CPID $FD Definition 
Control 
Byte # 
Bit7 
Bit6 
Bit5 
Bit4 
Bit3 
Bit2 
Bit1 
Bit0 
1 
Disable All 
System 
Outputs 
1 = ENABLE 
0 = DISABLE 
ECU Reset 
1 = ENABLE 
0 = DISABLE 
Learned 
Source ID 
Reset 
1 = ENABLE 
0 = DISABLE 
2 
3 
4 
5 
B2.1 Disable All System Outputs. 
A scan tool implementation of this device control allows the user to 
deactivate all output devices of an ECU simultaneously or, if this is not possible, freeze the output(s) at its 
(their) current value. This prevents random behavior or periodic switching of loads during a current 
measurement. Upon receipt of this device control, the ECU shall verify that none of the device control limits are 
exceeded. 
When this device control is active, all device controls assigned in other CPIDs for that ECU can be 
activated/deactivated independently by the other CPID (overrides CPID $FD for that output). 
This device control will only be allowed if all the following are TRUE: 
1. Vehicle Speed = 0. 
2. Engine is not running. 
A TesterPresent ($3E) message is required to keep this device control active.
B2.2 ECU Reset. 
Implementation of this device control allows a tool user to force the ECU to restart the 
application program (soft reset). Previously learned configuration data, adaptive factors, and other long-term 
adjustments shall not be reinitialized. The actual performed action is implementation specific. 
This device control will only be allowed if all the following are TRUE: 
1. Vehicle Speed = 0. 
2. Engine is not running. 
The ECU must respond to the request prior to performing the reset.