Component Description
When the driver needs to change gear position the driver selects PRND or S by pressing a GSM button. The GSM reads the switch inputs and sends a request over the High Speed Controller Area Network 2 (HS2-CAN) through the GWM over the High Speed Controller Area Network 1 (HS1-CAN) to the PCM. The PCM receives the input from the GSM, combines in vehicle conditions to determine commanded transmission range then sends a command to the TRCM through a GWM over the High Speed Controller Area Network 2 (HS2-CAN). The TRCM will act on the command from the PCM by moving the transmission to the commanded position via a selector lever shift cable. The PCM reads the transmission range sensor (TRS) and confirms the correct position has been achieved. The PCM then sends a message to the GSM and the IPC to display the current transmission range.
GSM
Each GSM button has three individual switch contacts that are used as input that the button has been pressed. If one switch contact is seen as nonfunctional the system will still work properly. However, if two switch contacts fail the button is no longer deemed reliable and a fault message is displayed. When park is selected above 5 mph neutral is provided along with a message in the IPC. The Brake Transmission Shift Interlock (BTSI) CAN signal is used for normal function to shift from P.
RCM
The shift by wire system uses the driver's seatbelt buckle as one of several inputs used to determine driver presence. If the buckle is deemed faulted for any reason the system reads this as "unbuckled" so that any time the door transitions to "open" below a set speed the TRCM will be commanded to return to park.
TRCM
The TRCM actuates the shift cable in place of a conventional selector lever. It receives commands from the PCM and GSM via High Speed CAN. The shift cable connects the TRCM to the transmission manual lever.
Brake Transmission Shift Interlock Override
This allows the shift by wire system to override the Brake Transmission Shift Interlock (BTSI) through a override switch located in the floor console. To activate this mode, press and hold the override button with a small screwdriver (The GSM will flash once after one second), press any non P button then release the override button. If vehicle system has low voltage, this function will require the vehicle to be powered using an auxiliary power source.
Selector Lever Cable
The selector lever cable consists of:
- a cable that connect the transmission manual control lever to the TRCM.
- an adjuster locking tab at the transmission manual control lever.
IPC
The IPC receives signals from the PCM and displays the current range of the transmission on the PRNDS. Under some circumstances messages from the shift by wire system will also be displayed for the customer on the multifunction display. For example, "Press Brake to shift from Park" is displayed if a non-park button is pressed when in P and the brake is not pressed.
BCM
The BCM provides Brake Transmission Shift Interlock (BTSI) information, GSMLED intensity status, electronic door lock commands, and ignition status to the GSM, TRCM and PCM. The BCM is also responsible for customizing BTSI and other signals based on local regulations and vehicle features.