Can anybody tell me what this is?

[option13]

I've owned my 94 since it was new so I know this is from the factory.
I just bought a trailer and I wanted to see if there was a connection for the brake lights and when I crawled under the rear bumper I saw this hanging right behind the bumper.
I've asked the people at the auto parts stores and they aren't familiar with it. Can anyone tell me what it is? Sorry for the poor quality, I'm an engineer not a photographer

 

[Delancy]

Auxiliary fuel tank?

 

[george_tlc]

Yes, it's the connector for the factory (in the rest of the civilised world) subtank sender & empty sensor.

From my subtank install:

cheers,
george.

 

[option13]

Ah...mystery solved.
Thanks guys.