'86 T-type vacuum line to pass side

[ttypetex]

What is the forward most module of the four module group located on the passenger side? The back three are ESC, fuel pump relay, and a/c compressor relay, but what does that vacuum module control?

 

[Pittsburghkid]

That's the map sensor unless you have a digital dash then it's a hobbs switch.

 

[mikestertwo]

Most likely the MAP sensor that runs your boost gauge.