Pictures of parts on 1990 UCF10
Since people always seem to ask about this here are pictures, and I will keep adding when I can.
Top left is under the engine compartment fuse box cover as you can see it shows what fuse does what circuit.
Top Center left is the same thing only moved more to the left.
Top right hand is the data port and the cover showing the id of terminals.
Next row down rh shows the fuse box of a non airsuspension car.
Same row in center is another pic of the data port cover in an attempt to show the terminal placements.
Very bottom is a disconnect switch, I didn't want to goof up a good ground cable end with the clamp to put this on so that's why its on
the positive, any car going in a garage of mine gets a disconnected battery, plus this is a good deal if you for some reason have an emergency and need to quicky disconnect the battery and don't have time or tools to fumble for.

 

Is the material brass? If so, you may have a problem caused by the galvanic corrosion.

 

Please edit your post with the year of the LS400 the pictures are from, as things are different in different years.

 

See the red stuff? It won't corrode.

 

1990 Fusible links.
On the left side near the hose clamp in the cable nut that needs to come off. The little doors clip over the protrusion to latch I used finger nail to open them.
Its a battle the wire loom may need some clamps removed to be able to pick it off the cable stud where the nut was. And notice below the right hand door the hook that is what the unit slips onto and holds that side of it. To remove the fusible links there are bolts inside those doors.