For the Isuzu engine (commonly found in Isuzu Elf N-Series trucks), the Engine Control Module (ECM) pinout and wiring information is typically detailed in the official Isuzu Workshop Manual (Engine Control System - Section 1A) Primary Pinout and Wiring Resource
Workshop Manual (N Series) Engine Control System (4HL1 Engine) Manual & Pinout Links isuzu 4hl1 ecu pinout link