Yes you can do it using a single pole switch and a bosch 5 pin relay. you have it wired up to your horn thru the relay to stock horn, then when you hit your steering wheel and get your factory horn. Activate the switch and you send the horn signal wire thru the relay then to solenoid. I’ll post up to describe how to do it.
Bosch five pin relay, it’s a normally open or normally closed relay.
Terminal: 85 to ground
86 to a switch in the cab (this needs to b e a 12 volt power signal)
30 to the horn from the cab ( could tap out at horn and run wire back in to cab
instead of taking apart steering column)
87 to factory horn
87a to the solenoid
If you want the normal horn to work most of the times and be able to flip a switch to gets to horns to blow, then switch 87 and 87a around.
So once the 12v pin 86 is activated (via my switch) it will close the relay and direct the horn button signal to the air valve solenoid, once pin 86 is de-activated, the horn button signal will pass through the relay to the stock horn, correct?
or just a standard 3 prong switch. cut factory horn wire and run it to the middle prong. the side of the cut wire going to the stock horns goes on one side and then the wire to activate your air horns on the other side
^^ right. He could also use a DPDT and not use half of it…if he found one without center off.
Looking at the Radio Shack website - only a couple of their SPDT toggles actually say “center off”. The rest do not. So rc10mike, just walk into a Radio Shack or another electronics store and tell them what you want. SPDT or DPDT with no center off.
This is getting funny.
Poles = number of separate circuits
Throw = number of contacts that can be connected in each circuit (independant of switch positions) i.e. center off
A DPST is basically 2 SPST switches in the same box and would have 4 pins.
The only way that would work is if 1 circuit was N.O. and 1 circuit was N.C. And you would have to use a jumper wire to make a common.
He needs a Double Throw switch. They come as 3 position (with center off) and 2 position. It will have 3 terminals (in a single pole configuration). He only needs one circuit.
If, by chance, he finds a DPDT switch with no center off it will have 2 circuits and 6 terminals. He can leave half empty.