Anyone have an idea what this plug is for? Just for reference that's the break fluid reservoir on the left.

 

What year/model ar you working on?

 

That would help! 87 Targa

 

Do trhe power mirrors work? I know they use a round plug and have a connection in that area.

 

They do. I can see the plug you are talking about. It's located about 8 inches or so behind this one.

 

I have an 88 cab and just looked for this plug. I only see one further back with a blue dot on it. It looks very similar to the one in your picture and is plugged in. Nothing near the brake fluid reservoir.

 

yeah thats the same one he is talking about , you can see it runs off to the same place... looks like same colour wires too.

 

Emac911...is your Cab top motorized?
If it is, I think it might be a connector for the motors.

Ercondo...that means on your car it might be an unused connector.
Now go drive that car

 

Non motorized cab top. Could it be cruise control or power mirrors?

 

I have the exact same connector on the targa and its disconnected.. 87 Targa carerra. following this tread