Nope that is a solenoid that will shut off the vacuum when the door is opened, while the engine is running. Also their should be a check valve before the solenoid valve, to help keep it dropping while the motor is in a low vacuum mode, aka your foot in it!

 

A PO had put a gas tank valve on my step and it works great,,,, that is for a vacuum step!

 

I can get you some shots of my set up if that would help!?

 

Good system if all is working good. Only problem is that if there is any leak in the system, when on a long pull and low vacuum, the step would drop down. A lot of the owners have disconnected the switch to let you know the step is down. It would just keep coming on. Quite annoying! Mine at present is disconnected. Have not tried re-connecting yet.

I may make it a manual only step. the aluminum on on there does not look that good..