Name this part? Air brake related

[CarolinaHD]

Trying to figure out what this little solenoid/switch is called so I can figure out where the wires go. 1 black wire, 1 white wire. Mounted on the yellow air line coming right out of the firewall. Originally ran somewhere into this wiring rats nest for the bucket and outriggers.
Can't find it on any diagrams or in the service manual.
All the brake functions and warning lights operate as they should. Thinking it might have been added on by the upfitters but need to confirm. Thanks for any help

2009 gmc c8500

 

[Jody Treadway]

@braxton357

 

[braxton357]

Definitely an add on. Gm doesn't use those old style brake switches theirs all have delphi connectors. Not really sure what it might control, I know my (gm topkick) bucket truck is an auto and won't let you drive while the bucket is in the air.

 

[getstucksome]

That looks like a hobbs switch - basically a solenoid that activates and deactivates at differing pressures. I agree that it was probably an add on.

 

[CarolinaHD]

Thanks everyone! That's what I figured but wanted to be sure

 

[jeepinmatt]

I know my (gm topkick) bucket truck is an auto and won't let you drive while the bucket is in the air.

What's the fun in that?

 

[Croatan_Kid]

What's the fun in that?

For real! Just think about how much fire you could spread with @jeepinmatt up in the bucket, driving along, and him up there with a drip torch and/or flame thrower

 

[rodney eppes]

Wonder if it was some sort on Line-lock, on the brakes?

 

[WARRIORWELDING]

Wonder if it was some sort on Line-lock, on the brakes?

Most likely a signal supplied when brakes are activated and allows auxiliary equipment to operate. I've seen them activate something as simple as lights.