ok so driverside head light is very dim i mean like as dim as the sidelight, when i unplug the passenger side it goes off completly, i have run 12+ and ground to the buld and it works perfectly, it appears a ground is missing but i pressume there is a break in the loom between the passenger and drivers headlight, also when on main beam the blue light on dash does not no longer work,

Mark

 

On a Subaru the switched side is to earth, so check fuses, relays and switchgear as well.

dunx

 

Is this an H4 (2 filament bulb), may just be bad earth connection in the plug at the bulb. Try tightening the curly bits in the plug with pliers. I had a loose connection on a 01WRX years ago caused by the connector being so tight I destroyed a bulb getting it off which bent the claws loose on the connector causing the poor connection later.