05 western star gauges schematic

Had the #### plug backwards. From the schematic . Managed to get photos of the plugs in just the right light...
Starting over...

 

So, at the spedo we have battery power but no ignition power. There is a good ground with no back feed from anywhere. On pin 4 with the lights on there is 8.86v but with the door open it goes to 12+v. Both pins 5 & 6 low voltage data streams check good.

Data star
No ignition power but battery power checks good.
Ground wire checks good continuity wise. Pin for is dead as well "backlight" powered by ignition so expected. Both 5&6 check good low voltage on data bus. So there is no ignition power to either but it comes from the same source . Fuse f20 supplies this traced back to fuse panel . Fixed wire and replaced fuse. It's only 5 amp so it doesn't take much. Too many splices in the factory set up