SHROUD GP 4775334 - Caterpillar

Introduction
The engine supplies power to the ECM. The ECM powers the following components:
All sensors
The control valve for the fuel injection pump
The solenoid for the wastegate
Diagnostic connector
Electronic unit injectorsThe glow plugs are powered directly from the battery.ECM Power Supply
Illustration 1 g02720990
Typical example
The power supply to the ECM and the system is drawn from the 24 V or the 12 V battery. The power supply for the ECM has the following components:
Battery
Disconnect switch
Ignition keyswitch
Fuses
Ground bolt
ECM connector
Machine interface connectorThe schematic for the ECM shows the main components for a typical power supply circuit. Battery voltage is normally connected to the ECM. The input from the ignition keyswitch turns on the ECM.The main relay will remain energized for a time period after the keyswitch has been turned to the OFF position.The wiring harness can be bypassed for troubleshooting purposes.The display screen on the electronic service tool can be used in order to check the voltage supply.Power Supply for the Pressure Sensors
Illustration 2 g03735137
Schematic for the pressure sensors on the ECM J2 connector
Illustration 3 g03735138
Schematic for the pressure sensors on the ECM J1 connector
The ECM supplies 5 VDC through the ECM connector to each sensor. The power supply is protected against short circuits. A short in a sensor or a wiring harness will not cause damage to the ECM.Power supply for the Glow plugs
Illustration 4 g03735160
Typical example
The ECM supplies 5 VDC through the ECM connector to the glow plug control unit. The glow plug control unit controls the glow plugs.Power Supply for the Diesel Exhaust Fluid (DEF) Dosing Control System
Illustration 5 g03735161
Typical example