TUBE AS 5014281 - Caterpillar

ECM Pull Down Voltage
To aid in diagnostics of electrical circuits that are controlled by the ECM, an internal "pull down voltage" is connected to ECM switch to battery type input circuits.During normal operation, the switch contacts that are allowing the connection to a voltage source will hold the circuit high. When circuit conditions such as a loss of power to the switch supply voltage, a disconnection in the switch circuit or an open circuit will allow the circuit to be pulled low by the ECM pull down voltage. This condition will result in a below normal voltage condition at the ECM contact. As a result, the ECM will activate an FMI 04 (voltage below normal) diagnostic code for the affected circuit.Input/Output
Illustration 2 g06198622
Power train inputs and outputs
(1) Transmission ECM
(2) Engine ECM
(3) Aftertreatment ECM
(4) Chassis ECM
(5) Eco Mode Status LED
(6) Eject / Body UP Switch
(7) Hydraulic Tank Filter Bypass Switch
(8) Key Start Switch
(9) Parking Brake Sensor
(10) Parking brake Pressure Sensor
(11) Retarder Lever (I-II-A) (Except 740GC)
(12) Transmission OIl Filter Bypass Switch
(13) Transmission Hold/Waiting Brake Switch
(14) Front, Center, and Rear Axle Brake Temperature Sensors
(15) Brake Pressure Sensor #1
(16) Brake Pressure Sensor #2
(17) Engine Speed Sensor
(18) Assisted Hoist Enable Switch
(19) Primary Starting Pressure Switch
(20) Speed Limit Switch
(21) Service Brake Pedal Switch #1
(22) Fuel Level Sender
(23) Hoist Control Position Sensor
(24) Hydraulic Oil Temperature Sensor
(25) Secondary Steering Relay
(26) Service Brake Pedal Switch #2
(27) Transmission Control Position Sensor
(28) Torque Converter Temperature Sensor
(29) Transmission Oil Temperature Sensor
(30) Transmission Intermediate Speed Sensor #2
(31) Transmission Intermediate Speed Sensor #1
(32) Transmission Output Speed Sensor #1
(33) Transmission output Speed Sensor #2
(34) Brake Oil Filter Bypass Switch
(35) Emergency Brake Switch
(36) Starter Motor Relay
(37) Starter Motor / Park Brake Solenoid Return
(38) Demand Fan Solenoid
(39) Service Brake Charge Solenoid
(40) Hoist LOWER Solenoid
(41) Hoist Raise Solenoid
(42) Parking Brake Solenoid
(43) Main Relief Valve (eMRV) Solenoid
(44) T/C Lockup Clutch Solenoid
(45) Transmission Solenoids
(46) Backup Alarm / LightsThe CAT Data Link is used to communicate with the other electronic control modules on the machine. The CAT Data Link is bidirectional. The CAT Data Link allows the sharing of information with other electronic controls.
The Power Train ECM receives the harness code input from the Caterpillar Monitoring System.
The Power Train ECM sends the following information to the Caterpillar Monitoring System: engine speed, machine ground speed, parking brake switch status, transmission speed selection, and service code of the transmission.
The monitoring system displays this information for the operator or for service personnel.
The Power Train ECM communicates with the engine ECM to allow controlled throttle shifting.Inputs
The machine has several input devices. Input devices inform the ECM of the operating conditions of the machine. The machine has two types of inputs, switch inputs and sensor inputs. The switch inputs of the ECM are provided with the following signals from the switches: an open, a ground and a +battery. Sensors provide a constantly changing signal to the ECM.Outputs
The ECM responds to decisions by sending electrical signals through the outputs. The outputs can create an action or the outputs can