26 SENR9977 Systems Operation Section ECM Power Supply g01141374 Illustration 32 Power Supply for the ECM The power supply to the ECM and the system is drawn from the 24 volt or the 12 volt battery. The power supply for the ECM has the following components: The display screen on the electronic service tool can be used in order to check the voltage supply. Note: Two wires are used to reduce resistance. Battery disconnect switch Key start switch Fuses Ground bolt ECM connector Machine interface connector Note: The ground bolt is the only component that is mounted on the engine. The 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 key start switch turns on the ECM. The wiring harness can be bypassed for troubleshooting purposes.