Helix 10 g2n shuts off when motor started

[setsail26]

Yes, I know this is a common problem, and in fact one I have dealt with before. This time the wiring and battery check out 100% I have no voltage loss from the battery to the helix. Battery is less than a year old, tests to 1350 CCA. Only the finder on the console turns off, the two helix's at the front stay on. They are on the same fuse block which is directly wired to the battery. Battery is iconic lithium 125 ah cranking battery. Motor is 200 hp pro XS. If the battery and wiring are good, am I left with the finder being the problem? Is there something else I should look at? Appreciate any help.

[Wayne P.]

Did you set one of the boxes digital readouts to see what the unit is seeing?
Put one of the other units at the console and see if it remains on when starting the outboard.

[setsail26]

Unit says 12.3 volts, multimeter says 13.4 volts at the plug to the unit.

[Wayne P.]

Should not loose 1.1V with a load, should be less than .5V.

[1BADAIR]

Swap one front to rear?