1. Define every endpoint
Give each connector a unique identifier and record the component, part number and view used in the drawing. Include the ECU end and every branch. Define whether the delivered item is a connector set, flying-lead harness or terminated adapter, because each leaves a different amount of installation work unfinished.
2. Use a cavity-to-cavity worksheet
For every circuit, record source connector and cavity, destination connector and cavity, signal name and wire label. Add wire specification where established by the installer. Treat colour as a supporting identifier, since a repaired or revised loom may use a different colour while retaining the same cavity assignment.
3. Plan routing before cutting
Measure along the actual installation route and include branch points, strain relief and service access. Mark heat, vibration, moving parts and water exposure. A straight-line distance between ECU and engine is not a finished branch length. Review the route with the installer before selecting protection and finalizing terminations.
4. Keep grounding model-specific
Separate power grounds, sensor returns and shields in the worksheet, then follow the exact ECU manual for their destinations. Do not combine them based on a generic rule from another brand. Record any shield termination explicitly so later repairs do not silently change the original design.
5. Agree on acceptance evidence
Ask for the final pin map, connector list, revision and agreed inspection results. Checks should be appropriate to the disconnected electronics and manufacturer instructions; do not apply a generic high-voltage insulation test to attached ECU circuits. Identify unfinished ends and label them. The handover should let another installer reconstruct what was built.
Official references
Editorial summaries; use the matching manufacturer manual for actual wiring and calibration.