When doing repairs on say trailer lights and i need to leave key on awhile, what relay or fuse should i unplug, i did take glowplug main supply off battery so no gp operation, would fuel pump cause any problems if left on and engine not running or ficm since both on anyway while running.

 

None. No need to remove any

 

ok,thanks, i didnt want to kill my batts while doing stuff.

 

Go ahead and attach a battery charger to the batteries during your wiring work to avoid the chance of battery drain and you'll have one less thing to worry about.