Hi Chris,
Your 12V/20Amp DC Switch will work just fine. The important thing here is that you use a 12Volt Direct Current Switch which is rated equal to or greater than the amperage of the fuse. The higher the amperage rating of the switch (at 12 volts) means the more reliable the switch will be because the switch will be made stronger to take the extra current and the Fuse will blow at whatever it is rated at. A 240Volt AC(Alternating current) switch may or may not work for very long, because AC switches are made to work a little differently than DC switches. Direct Current is more severe on switches than Alternating Current when switched on and off. DC current causes greater arking on slower moving switches (AC) so good DC switches are made to disengage or engage more quickly than AC switches to alleviate arking across the make/break joint which will destroy the contacts prematurely. The switches have to match the Voltage, and the Current but most importantly it has to match DC or AC. Bikes are 12 Volt DC, use the correct switches for better results and less problems. Of course some AC switches have worked and will continue to work on DC circuits but they are not designed to and maybe won’t last as long. As an interesting example; In Australia when building motor homes/Caravans with 12 Volt DC electrical systems, it is illegal to use 240 volt AC Sockets and light switches. Only electrical fittings rated for 12 Volt DC are supposed to be used for safety reasons.
Again, I have tried to put it in the simplest and easiest way to understand what I was taught to do.
John
Thanks, John. That’s very informative.
I would never have thought that there was such a difference between AC and DC switches. That just illustrates why I chose mechanical engineering over this electrickery malarkey.
No Problems Chris, I got caught out a couple of times in the past. It is also one of the reasons they use relay/solenoid switches on 12/24 Volt DC systems, because they are a fast action on and off switch. The other reason is to not put high amperages through your ignition switches etc. Also the reason they put a condenser/capacitor across the old points ignition systems to stop excessive arcing (yep I spelled it right this time) on the contacts. As I have said before it is a bit tricky sometimes but if I can help or offer advice to you or anyone else, I am quite happy to do it.
John
Hi, John,
I’ve successfully installed the override swith for the fans. All is good.
I then thought afterwards that it would be a good idea to fit an LED to said override circuit to alert me to when the fans are running.
I’m led to understand that said LED would need to have a 12v supply into it, with the earth being connected into the upstream tapping for the switch (logic - the switches are in the earth return from the motors, so by connecting the earth upstream of the switch it would allow the LED to illuminate if either the thermal or manual switch is closed).
If that is correct, can you suggest an easily accessible 12v supply that is switched by the ignition switch that I can tap into? I might as well fit the LED while the fairing’s off.
Thanks.
Hi Chris,
Let me think about that will get back to you. As a first thought I would think the easiest way would be to replace your toggle switch with an illuminated switch but because it is switching the earth side will have to think more about it. The other thing is VF1000Fe put an illuminated switch on his bike so he will know what he did to get it to work. Fitting a relay might work with power from the ign switch or fans switching a positive to a light at the same time it switches the negative to earth. garyb fitted a relay so he should know how to do that. Let me think about it and get back to you, because you can’t switch a light on from the earth side of the circuit unless you have power on the other side. Also the little I know about electronics if you use a true LED then you will have to put the correct size resister in circuit for twelve volts supply. I might try some practicle things over the weekend to jog the memory.
John
As you can see here I used the switched 12V from the indicator lights panel (turn, oil, neutral, …)
You need a resistor to operate LED at 12V. Normal red LED with 20 mA current draw would need 560 Ohm.
Hi Chris,
Sorry had a brain fade yesterday. 
I am attaching a copy of the mud map showing how to fit the led. Easier to get to the positive going to the fans and also the negative going to the Thermo switch. This should give you a light when the fans run regardless of which switch you use because the positive comes from the fans. You will need a 560 Ohm resister according to Faxe and an ordinary 12 volt Led. If your new switch is working then leave it as is. If you run a double wire down to the fans then connect as they are in the drawing then you should get a light when you should. Another way to ground the earth wire is just join it to the earth side of the switch that you have just installed. If you decide to install a normal 12 volt globe light then you don’t need the resistor in the circuit. Now I just have to remember how to attach a file.
John
Thanks, John.
It’s becoming more evident to me that choosing mechanical engineering over electromagickery was a good move.
Your mud maps make it much clearer than the page of random lines otherwise known as a wiring diagram does.
Thanks again.
Chris.
No problems Chris. I am sure you could teach me a lot about mechanical engineering. If you look at the mud map, with the alternate Thermo switch at the bottom, this would also be the right wiring for an ordinary manual switch. Hopefully that is the way you wired it up.
John
I put the manual switch in parallel with the thermal switch, tapping into the black and green wires that go into it behind the headlight.
It works, anyway.
That’s good. How it should be.
John
It Depends,…
Red LEDs (and yellow and green) run at 2.2Vdc White & Blue LEDs run at 3.3Vdc
Also your bike Running Voltage is 14Vdc
Best to use 680ohm resistor (1/4 watt).
Also better to use a “clear” LED rather than “diffused”.
Diffused are not seen as bright, but clear will definitely be seen.
Also LEDs are “Light Emitting Diodes”, key is the term Diode, it only conducts in one direction. If it don’t light, flip the LED leads.
Or you can just get a 12V incandescent Illuminated Push-On/Push-Off Switch (comes with different color gels).
Thanks.
Now to the eye rolling, face palm question.
I’ve bought a nominally 12v LED for the job (yet to be delivered) that is pre wired and nestling in an 8mm holder.
The vendors claim that it’s ready to just ‘plug and play’.
Would it be safe to conclude from that that the necessary resistor has already been incorporated?
Is there any way to determine whether it is, in fact, plug and play? I’d imagine that a simple resistance measurement with a multimeter would suffice?
Remember, as previously stated, I am to electronics what Liberace was to rugby union, and if I can’t hit it, I can’t understand it, so use words of one syllable if you reply.
Thanks again.
Hi Chris,
VF1000Fe is absolutely right and he sounds like he knows a lot more about electronics than I do but, If you decide to go with an incandescent push/pull switch the light will not work because you are only switching the negative to earth. However you can keep the manual switch that you have and install just an incandescent light instead of the Led and the resistor, like it is in the mud map. Jaycar Electronics have a good selection. A normal incandescent light would be easy to install alongside the manual switch that you already have (because of the switching of the negative to earth with no 12vdc supplied). This would give you a light on whenever the fans are on, which is what you originally wanted. You can get Led lights that have the resistors included for 12Vdc so if that’s what you bought then you obviously don’t have to worry about resistors, just wire it up like the Mud map less the resistor. It really is a matter of personal choice. You already have half the job done, so you just have to install the light, whichever one you prefer. Easy 
not so bad after all. Let me know how you get on.
Good luck
John
Mission accomplished. All installed and functioning.
I ended up making up a loom for the LED power and the two wires from the thermo switch and another one from the switch & LED installation so that the cluster can be removed simply by unplugging the extra wiring.
Connected everything up and it all works. The LED even comes on when the thermal switch trips in, too.
Thanks for your pointers, John. The installation was pretty easy once I knew what should be connected to where (see previous posts about my bike electrics expertise). It actually looks quite neat, almost like it should be there as standard.
Well done Chris. I saw the previous posts and had a laugh at them, maybe you won’t feel so helpless now. I feel the same about electrics verses electronics sometimes. I have a basic knowledge about electronics but once it gets past Led’s and resistors I’m stuffed.
Stay safe.
John
Be glad there is no radar on board. In RF circuits need voodoo to work 
I’m on a roll!
I’ve fitted the override switch for the fuel pump relay too.
I need a lie down now.
The extent of my knowledge of electronics is that it works by using magic smoke, and if the smoke escapes it stops working.