double check me please

Ok I am going to put a solenoid into my air system so I don’t have to manually regulate my psi. I have Viair part # 90101 for 85-105 psi my my horn has nice tone at that range and its within tolerances of the system. my compressor is a 30 amp max and the solenoid is 20 so I need a relay. Just to make sure the flow of electricity will go power source to relay to solenoid to switch to compressor correct ? and also will a normal relay picked up at autozone work just fine ?

What you’re thinking of as a solenoid is actually just a simple switch (the pressure switch on the tank right?). A solenoid involves an electric coil (e.g. there’s one in the relay and in the air valve that opens to blow your horns)

In the relay, the solenoid wires are also called triggers or signal lines. As they energize the coil, an electromagnetic field inside the coil throws an internal switch which lets the main power run through the relay.

Check post #8 here for a relay wiring diagram.
https://www.trainhornforums.com/showthread.php?t=6366

As long as your relay is rated to handle the amps from your compressor you should be right. Just make sure you have everything fused and most importantly a good ground connection.

DBO thanks for the quick education on the terms and functions you seam to educate me a little more every time you reply to me lol (that’s a good thing). I really don’t know a lot of the correct terms for the parts lol. But yes what im incorrectly calling the solenoid is the pressure switch at the tank. But I’m glad I have the correct wiring plan for the switch thanks for the reassurance.

** I would not use that diagram **

Reason being: That diagram has the pressure switch on the high current (load) side of the relay. If the compressor draws 30amps and the pressure switch is rated for 20amps, you will burn up the pressure switch.

Put the pressure switch on the low current coil side of the relay…usually between the ignition source and the relay.

I can probably find a diagram if you don’t know what I mean.

Here is Viair’s diagram.
http://viaircorp.com/Schematics/singlec_wd.pdf

I took your advice and wired my pressure switch according to the diagram you linked to me its working great for me. and its REAL nice not having to monitor the tank pressure and flip a switch to manage the pressure just turn on the main switch and let pressure switch handle it all for me. Thanks

Glad to hear it is wired and operating safely.