Ground Switch

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In my wiring adventures I'd never thought to use a switch to go to ground. But then I got stumped by the Domino switch on the Ducati. Since it's aftermarket and would look nice on a Norton I thought I'd include my learnings here. What threw me off is that I have a custom motorcycle circuit board that just has SPST relays and I couldn't get the horn to work. And I was scratching my head trying to figure out the kill switch (there, I said it, suck it up).

It wasn't until it dawned on me that I couldn't use those relays and would have to use other ones to make both these item work. The SPST relays were linked on the board so I couldn't isolate the grounds for the switches. I'm sure someone will tell me I'm wrong.

Ground Switch

The horn button grounds out when you press it. I kept expecting 12v at the horn button and no matter how many times I pressed it that never happened. :oops: By using a different relay I can use the 86 to ground (from the switch), apply power at 85 and 30 and have horn noise come from 87. I'm using some Hella relays and for some reason they didn't like those numbers and just use 1-5. Germans... :?

Ground Switch



Ground Switch


On the kill switch when you press the button the two wires connect. You can imagine that this made my head hurt. Here I'll ground 86 and apply power to 85 (both through the kill switch), 30 will be fused power and 87A will have power to the ignition box until the kill switch is pressed (then it will flip to 87 and no power at the ignition).

How did I do? And yes, this is negative ground.
 
Took me a while to get the horn to work. There are three terminals on the board that are suppose to be switched power. I forgot that one of them is a ground. :? Guess which one I tried first...

When I finally got it all hooked up and hit the horn button I just about went through the roof. It's plenty loud. :mrgreen:

Kill switch is next. How can I possibly screw that up?
 
I have a Benelli that the horn works on the same grounding out principle. Havent figured it out yet :?
 
Ok, horn and kill switch working as diagramed. I'm slowly learning just enough to be dangerous.
 
Tintin said:
swooshdave said:
I'm using some Hella relays and for some reason they didn't like those numbers and just use 1-5. Germans... :?

The reason is called DIN 72552 and it's quite useful actually.


Tim

I was being very sarcastic, I'm sure the story about the other numbers (86, 87, 30...) is quite archaic. :mrgreen:
 
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