THEORY OF OPERATION - CONTINUED
POWERTRAIN - CONTINUED
CAT Data Link.
CAT Data Link is a communication link used for data movement between electronic controls. CAT Data Link
allows communication between powertrain ECM and Messenger. CAT Data Link is bidirectional, allowing power-
train ECM to input and output information. CAT Data Link is not a visible component; it consists of internal pow-
ertrain ECM circuits, related harness wiring, and diagnostic connector. CAT Data Link and powertrain ECM are
connected at pin-out J1-10 and pin-out J1-20.
Powertrain ECM and Messenger use data that are sent back and forth on CAT Data Link. Some of this information
Powertrain ECM receives service commands from Messenger to change powertrain electronic control sys-
tem operating modes. Service commands can direct powertrain ECM to read and clear service codes stored
in powertrain ECM memory.
Powertrain ECM receives harness code input from Messenger. Powertrain ECM determines sales model of
machine from harness code input.
Powertrain ECM sends signals to Messenger, which uses signals to report on powertrain electronic control
system status. Messenger alerts operators of status by illuminating corresponding alert indicators.
Powertrain ECM sends this information to Messenger: parking brake status, transmission direction, and
transmission speed. Messenger displays selected transmission direction and speed and uses this informa-
tion to show operator if parking brake is engaged or disengaged (TM 5-3805-291-10).
Torque Converter and Pump Drive Housing.
Transmission oil pump and hydraulic implement pump are mounted on torque converter housing. Torque
converter housing is between engine flywheel housing and transmission housing.
Gear turns drive gear for transmission oil pump and hydraulic implement pump. Pump drive flange is con-
nected to transmission oil pump by splines. Hydraulic implement pump is fastened to transmission oil
pump. Torque converter output gear sends power to input gear for planetary transmission.
Torque Converter (Freewheel Stator).
Torque converter is located at transmission input end. Housing is bolted to flywheel housing. Output
torque from torque converter enters planetary transmission through either Number 1 or Number 2 sun gear.
Gear that receives output is dependent upon direction clutch engaged.
Oil for torque converter operation is supplied by transmission oil pump. Oil from transmission oil pump
flows to torque converter housing where oil flow is divided. Transmission hydraulic control relief valve
and clutch solenoid modulating valves receive divided oil flow. Transmission hydraulic control relief
valve regulates P3 torque converter inlet oil to flow to torque converter at a nominal pressure of 80 psi
(552 kPa). Torque converter inlet relief valve limits oil flow to torque converter to a maximum pressure of
130 ± 10 psi (900 ± 70 kPa). Torque converter inlet relief valve is located in torque converter housing.
Transmission hydraulic control relief valve is located above torque converter inlet relief valve.
Torque converter outlet pressure is 60 psi (414 kPa).