LINK AS 8Y2204 - Caterpillar

Illustration 1 g02360196The Transmission ECU electronically interrelates with the following functions, sensors, inputs, and outputs:
OEM Components
Transmission Monitoring Lamps
Torque Converter Outlet Sensors
Transmission Sump Temperature Sensors
Transmission Filter Bypass Switch
Engine Speed Sensors
Converter Output Sensors
Transmission Speed Sensors
Oil Level Sensor
Transmission Shift Points
Neutral Start Function
Parking Brake
Torque LimitingNot all of the components in the diagram are required during basic vehicle operation.General Operation
The following electronic control modules communicate with each other through the J1939 data link: Engine, Transmission, Shifter, Selector, Anti-lock Brake, and Traction Control Systems (if equipped). These modules are share the internal information and may temporarily control other modules that are connected to the data link. Other devices connected to the data link, such as an instrument cluster, can display information that is broadcast over the data link. Other devices may use the data link in order to broadcast the positions of switches. The service brake and the parking brake are examples of switch information that can be based on the data link.Overview
The ECU provides the service technician with enhanced diagnostic capabilities. The enhanced diagnostic capabilities are available by using onboard memory. Onboard memory stores the possible diagnostic trouble codes for retrieval at the time of service. Service personnel should use the Caterpillar Electronic Technician (ET) for troubleshooting.There are no sensor outputs that are accessible to the customer. All sensor outputs are only available over the J1939 or the J1587 data link.Transmission ECU
The ECU is located on the top left of the transmission. The ECU has two connectors. The first connector is for the Caterpillar transmission harness. the second connector is for the vehicle OEM harness. The ECU is controlled by software that is developed by Caterpillar for this transmission.Shift Selector
The transmission shift selector is a J1939 device on the data link that communicates the preferences of the operator to the Transmission ECU. The shift selector has a display that indicates the current gear. The display also functions as an indicator for tasks that are related to service.Temperature Sensors
The ECU monitors the temperature of the torque converter oil at the outlet. The ECU also monitors the temperature of the transmission oil in the sump.Oil Level Sensor
The oil level sensor is used in order to check the level of the oil in the transmission. The operator may initiate this check with the controls that are on the shift selector. The ECU takes no action if the oil level is low. The operator is responsible for initiating any required maintenance. The check can be initiated under the following conditions:
The engine speed is at idle.
The transmission is in Neutral.
The vehicle is stationary.
The vehicle is level.
Transmission at operating temperatureSpeed Sensors
There are four speed sensors on the transmission. The Transmission ECU uses four speed signals in order to control the performance of the transmission. The ECU also uses the four speed signals for scheduling the shifts and in order to perform shifts. The speed sensors monitor the following:
Engine speed
Torque con