342-3063 3423063 Chassis Main Harness for 336D Excavator

Final Connections and Verification:
Double-check that every connector is properly attached and the harness is securely mounted.
Reinstall all guards, panels, and covers.
Reconnect the negative (-) battery cable(s).

System Check:
Turn the key to the ON position (without starting the engine) and check for any warning lights. Listen for any unusual relays clicking.
Start the engine and operate all systems (hydraulics, lights, monitors, etc.) to verify proper function.
Use Caterpillar's Electronic Technician (ET) software if available to check for any active or logged diagnostic codes.