Started with DEF/emissions derate codes. Machine was running but derated. Found broken wire between ECM J1 and SSR relay circuit. Repaired wire and regained power on pink wire feeding DEF-related modules. Now machine is a no-start. Current findings: CAN resistance checks good at ECM J1/J2 (~60 ohms) CAN voltages appear correct Checked NOx sensor circuits Unplugged both NOx sensors Tested sensor on large SCR can and DEF tank module Reduced active codes significantly following troubleshooting Harness has been double checked Following Komatsu service manual troubleshooting tree Machine ran before beginning electrical repairs, now crank/no-start. I have NOT located the SCR/DEF controller yet. Does anyone know exact location on D85PX-18 serial 22042? At this point I feel like I’m missing something simple.
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