View source for MG 4 Gear Selector


==General Information==
MG 4 uses a rotary gear selector. 

Neutral corresponds to the central rest postion, Reverse is selected by an anticlockwise twist, Drive by clockwise rotation of the gear knob. 

Park is selected by pressing the gear knob.

Selected gear is communicated by CAN.

The unit incorporates three LEDs across the top of the unit which correspond to Reverse, Neutral and Drive.

The knob itself lights up in Yellow when Park is selected.

=== Part Numbers ===
SAIC Motor Shift-by-wire : 11357121

===Pinout and Connector===

The shifter uses a 12 way connector, of which only 5 pins are connected.

Required plug is:
 Molex 347290122 : https://www.molex.com/en-us/products/part-detail/0347290122

When viewed from the rear of the unit, Pin1 is top-left, Pin12 is bottom right.

{| class="wikitable"
|+12-Pin Pinout
!Pin
!OEM Wire Colour 
!Function
|-
|1
|Black/Yellow
|12V
|-
|5
|Pink/White
|12V WakeupEnable
|-
|7
|Yellow/Blue
|PT-CAN Ext High
|-
|8
|Green/Yellow
|PT-CAN Ext Low
|-
|12
|Black
|GND
|}

=== Operation ===
On poweron, the selector will start in the PARK position, and this will be communicated in message 0x09D

To enable shifting three messages must be sent to the shifter, repeated at 50ms, CanIds: 0x047, 0x12a, 0x2b6 as described below.

Stopping sending the 0x47 message will cause the shifter to enter into PARK position and prevent a gear being selected.

Restarting 0x47 messages will re-enable the shifter and allow a gear to be selecte.

===CAN Bus===
The Powertrain CAN Bus has a baud rate of 500kBaud.

Most messages have a standard CRC-8-SAE J1850. (polynomial 0x1D)

CAN Messages are sent every 50ms.

Observed data is described below.
{| class="wikitable"
|+
!CanId
!Message
!Direction
!0
!1
!2
!3
!4
!5
!6
!7
|-
|0x09D
|Shifter Status (from Shifter)
|From Shifter
|CRC8 (bytes1-7)
|Counter 4-bit
F0-FF
|03
|POS1
|POS2
|<nowiki>F0|F1</nowiki>
|<nowiki>38|39</nowiki>
|FF
|-
|0x047
|Control Msg1
"Activate Shifter"?
|To Shifter
|CRC8 (bytes1-7)
|Counter 4-bit
00-0F
|45
|9B
|7F
|FF
|FF
|<nowiki>FE|FF</nowiki>
|-
|0x12a
|Control Msg2
|To Shifter
|CRC8 (bytes1-7)
|Counter 4-bit
F0-FF
|FF
|FF
|FF
|FF
|FF
|<nowiki>01|11|13|14</nowiki>
|-
|0x2b6
|Control Msg3
|To Shifter
|00
|00
|02
|00
|00
|00
|00
|00
|}


The Gear selection is communicated over CAN, and can be decoded as follows.

POS1 is sufficent to indicate the selected gear.
{| class="wikitable"
|+
!Selected Gear
!POS1 
!POS2
|-
|DRIVE
|05
|0A
|-
|NEUTRAL
|06
|09
|-
|REVERSE
|07
|08
|-
|PARK
|08
|07
|}

== Sample Code ==
Arduino Due sketch to control shifter : https://github.com/will-camper/mg4-shifter

== Forum Links ==
https://openinverter.org/forum/viewtopic.php?t=6604

==References==
<references />
[[Category:MG]]
[[Category:Gear Selectors]]