PIN-SPRING 1T0550 - Caterpillar

Introduction
The engine supplies power to the ECM. The ECM powers the following components:
All sensors on the engine
The suction control valve for the fuel injection pump
Diagnostic connector
Electronic unit injectorsThe glow plugs are powered directly from the battery.ECM Power Supply
Illustration 1 g03590180
Schematic for the electrical power supply circuitThe 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 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 g03598889
Schematic for the pressure sensors on the P1 connector
Illustration 3 g03650217
Schematic for the pressure sensors on the P2 connectorThe ECM supplies 5 VDC volts 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 g03590326
Schematic for the glow plug starting aid circuit