Hey guys wondering if anyone could help me out here i have a sierra cosworth 4wd im in the process of putting back together, the issue im having is i have no power to the speedo head/clocks

if i remove the plug i have earths and one random 2volts from the 12 pin plug. Would anyone know what powers the unit? Obviously ive checked fuses relays battery voltage. I can power up the second wire in on the plug...black/yellow and the car will start run temp/fuel gauge rpm works. Also noticed no lights appear to be working on the dash or that side when i put the side lights on and no indicators but hazzards work fine.

Thanks Jason