Straight from the 06 FSM. Without it the trans will do nothing. without feedback from the ABS module it will not go anywhere.
TRANSMISSION CONTROL MODULE - NAG1
The electronic control system consists of various components
providing inputs to the transmission control
module (TCM). The TCM monitors transmission sensors,
shift lever position, and bus messages to determine
transmission shift strategy. After shift strategies
are determined, the TCM controls the actuation of
transmission solenoids, which controls the routing of
hydraulic fluid within the transmission, by moving a
sequence of four valves to make a shift occur.
The NAG1 electronic transmission has a fully adaptive
control system. The system performs its functions
based on continuous real-time sensor feedback information.
In addition the TCM receives information from
the PCM (engine management) and ABS (chassis systems)
controllers over the CAN bus. The CAN bus is a
high-speed communication bus that allows real time
control capability between various controllers. Most
messages are sent every 20 milliseconds. This means
critical information can be shared between the transmission,
engine, and ABS controllers. The CAN bus is
a two wire bus with a CAN Bus (+) circuit and a CAN
Bus (-) circuit. These circuits are twisted pairs in the
harness to reduce the potential of radio and noise interference.
The transmission control system automatically adapts to changes in engine performance, vehicle speed, and transmission
temperature variations to provide consistent shift quality. The control system ensures that clutch operation
during up-shifting and downshifting is more responsive without increased harshness. The TCM activates the solenoid
valves and moves valves in the valve body to achieve the necessary gear changes. The required pressure
level is calculated from the load condition, engine speed. Vehicle speed (from ABS module) and transmission oil
temperature, matched to the torque to be transmitted. The TCM is located under the left side of the instrument panel
