ENGINE AR 2W8404 - Caterpillar

The temperature sensor for the hydraulic oil informs the ECM of the temperature of the hydraulic system oil.Pressure Sensors
Brake Charge Pressure Sensor
Illustration 3 g06104960The brake charge pressure sensor informs the power train ECM of brake system pressure. The pressure sensor output is a pulse width modulated signal. The duty cycle of the signals will vary in proportion to the system pressure. These PWM signals are inputs to the Power train ECM. The Power train ECM provides 8 V supply and 8 V return for the sensor.Note: The machine is equipped with two brake charge pressure sensors.Parking Brake Oil Pressure Sensor
Illustration 4 g06104960The parking brake oil pressure sensor informs the power train ECM of the parking brake oil pressure. The pressure sensor output is a pulse width modulated signal. The duty cycle of the signals will vary in proportion to the system pressure. These PWM signals are inputs to the Power train ECM. The Power train ECM provides 8 V supply and 8 V return for the sensor.Switches
Switches provide one of the following types of input to the ECMs.
Open
Ground (-)
Battery (+)Switches are devises that have two states, Open and Closed.
When a switch is open, no signal is provided to the corresponding input of the ECM. This condition is also referred to as floating.
When a switch is closed, a ground signal (-) or a battery signal (+) is provided to the corresponding input of the ECM.Emergency Brake Switch
Illustration 5 g06165026The emergency brake switch is a two pole switch. Activating the emergency parking brake switch engages the parking brake.Service Brake Position Switch
Illustration 6 g03389656The brake pedal position switch is a mechanical switch that is used to determine if the operator is depressing the service brakes pedal. This switch has two outputs, one that is normally closed and one that is normally open. This switch provides a ground signal to the engine ECM. When the operator activates the switch, the outputs become reversed.Ignition Switch
Illustration 7 g03389670The ignition switch is a four position, two contact switch. The transmission ECM receives battery (+) voltage from the ignition switch in the (RUN), (START), and (AID) positions.Data Link
Cat Data Link
The Cat Data Link is an input/output of the ECM. The data link uses the connector for the service port to communicate with the Caterpillar Electronic Technician. A data link connection is provided for the product link.Note: The control for the product link provides a global positioning system for the machine.The data link is bidirectional. The bidirectional link allows the ECM to input information and output information. The data link consists of the following parts: internal ECM circuits, the related harness wiring, the service tool connector, and the connector for the product link.
The ECM receives commands from the Cat ET to change the operating modes. The Cat ET will read the service codes that are stored in the memory of the ECM. The Cat ET will clear the service codes that are stored in the memory of the ECM.
The ECM sends the input and the output information to the Caterpillar ET.Note: An