terminate multi-pin connector

do you guys have any tips on how to measure wire length or how to organize wire before terminate wire to multi-pin connector like ecu or deutsch connector without service loop and still got nice result behind the connector.

I use precise measurements, either make all wires the same length for small connectors, or slightly shorter wires for the center, and slightly longer the farther away from the center. If I am doing a 90-degree entrance (common for some long ECU connectors), I note the pin spacing, and add that much distance for each row of pins from the shortest. If in doubt, make it longer.

To measure wires, I use a small steel rule (6 inch, 150mm), and measure from the edge of the heat shrink.

Hope that helps.

do you arrange wire before doing concentric twist the branch that going to terminate to the connector. so each wire before terminate are positioned to the desire position on connector

You could do that. I don't do concentric twist, so I can usually move wires about to get them oriented like the pin layout. I think concentric twist often selects the core wires based on the type/size of wire so you can't always do it to match the connector. Just make sure you budget 3-6" extra wire at each connector end (yes, I've had to splice wires to extend them more than once!)