While putting the fuel tank back in my 87 I noticed this one plug dangling but it doesn’t seem to go anywhere. It’s coming out of the relay connector where another white wire in running in. Maybe a test point of some sorts?

 

I can't answer your question, but as soon as i saw that LUCAS sticker, my heart sank.

Back around 1988 after dealing with Lucas stuff on a '76 XJS in frustration and amazement (they didn't really do it that way, did they?), I had to take a flight someplace and I think it was on an L1011.

Anyway, they had these coat closets in the middle that went down into the floor elevator like, i saw the door open and it said LUCAS ELECTRIC on the elevator. I thought to myself, oh, no, we are all going to die.

Doug

 

After all the work I’ve done to this thing if I saw anything Lucas electrical that could kill me I’d walk away. But come to find out it’s what gets power from the inertia switch, solved my no power to main relay. Took a bit of canvassing a wiring diagram, but found the other end tucked back beside the tank.

 

Ah, yes, inertia switches.

I need to locate mine so i know where it is.

They can be PITA if tripped, but they do stop the fuel pump in the event of an accident or upset.

Doug