Killswitch Disengaged
March 15, 2010 10:17 AM

Help me kludge a solution to the broken kickstand killswitch on my scooter.

The kickstand killswitch on my scoot (50cc Cool Sports, Chinese make) disintegrated. View its remains here, here, and the connectors here. Basically it sits on the pivot point of the kickstand and prevents the engine from starting if the stand is down, or in the case of a destroyed switch, prevents the engine from starting, period.

I've checked numerous parts places online without success, but it has been suggested to me that it would be possible to bypass or kludge a solution.

According to the last parts place I spoke to, I should do this: stick a paperclip in two of the three holes, then turn the key on; if it starts to get hot, turn the key off and try a different hole. If it doesn't, it should turn over. Since this is currently my only mode of transport I'd really rather not destroy the scoot or its electrics, so any advice you can offer to restore my mobility would be greatly appreciated.
posted by waraw to Sports, Hobbies, & Recreation (17 answers total) 2 users marked this as a favorite
The switch would take power from the battery and supply it to the ignition. Why there are three leads is unknown, I can't imagine a ground being necessary in a switch of this type, but the switch may send juice to somewhere other than the ignition.

I would start by running a test lead from a voltage tester (you can get one pretty cheap at most hardware or automotive stores) from each prong to the scooter frame, testing continuity with ohms. You're looking to see if any of the three leads is a ground, it will show "0" or something very close if it is, and "OL" or infinity if it is not.

If none of the leads are ground leads, my shadetree take on it would be you could wire all three together. If one is a ground, you want to avoid wiring it in with the other two; tape it over.

Can you not find the switch on eBay or anywhere else on the tubes?
posted by maxwelton at 10:31 AM on March 15, 2010


I've been trying for several days, and have called numerous parts places today only to be told it's impossible to find.
posted by waraw at 10:33 AM on March 15, 2010


Is it possible from the wreck of your switch to see what came in contact with what when the switch was open or closed? It occured to me that they may send juice to a different destination with the stand down than with the stand up, though I'm puzzling as to why, in which case my "wire all three together" advice isn't the greatest.

If you can get at the back of the ignition switch, you should be able to use your tester to determine which prong in the kickstand switch goes to the ignition, and also determine (using the volt meter this time, assuming the battery is connected) which prong is live juice. These two are the ones that need to talk.

Continuity and multimeters.
posted by maxwelton at 10:36 AM on March 15, 2010


I'd guess the 3 pole switch has one hot, one to the ignition, and one to a warning light on your console that has been burned out for decades. Figuring out which is the live 12V lead is easy. Hook one end of your DMM to the frame and then probe the contacts. One will read something, probably 12V (some old vehicles use 6V systems). You'll need to jumper that 12V lead to one of the other contacts and you should be good to go. Most likely the 12V lead is the middle one, 'cause that is how switches mechanically work.

The only real danger here is not using thick enough wire in the jumper but I can't tell you what gauge to use. I can't imagine a scooter ignition draws a lot of current though.
posted by chairface at 10:58 AM on March 15, 2010


The only thing I would add is that since there's pretty much no chance of finding a compatible switch again, I'd go ahead and splice the wires directly (cut the two wires going into to the connector that need splicing, twist and/or solder the wires together, and wrap in heat shrink tube or electrical tape) rather than making a jumper, because jumpers can get corroded, fall out, or otherwise fail, and it'd suck to have that happen at 0100 in the rain, which is when it almost always happens. +1 to chairface's suggestion that the middle pin is the hot one too.
posted by hackwolf at 11:16 AM on March 15, 2010


It would help to clarify the behavior of the switch before it was broken. Did some of the electronics (but not the ignition) work when the kickstand was down? If so, do they work now? If there was no change in this behavior, it's probably safe to assume that the old switch was a SPDT (single-pole, double-throw) switch despite only needing to be a SPST (single-pole, single-throw). This is somewhat common; it costs very little extra when making a switch to add the extra terminal.

If that's the case, you'll have to connect the common terminal (usually, but not always) the middle to the correct terminal (which is closed when the kickstand is up). You have very little chance of causing any problems if you get this wrong, but it won't, obviously, work. Your best bet is to see if you can figure this out from your old switch, but failing that, the paperclip idea seems pretty reasonable.

Remember to be VERY carefull about your sidestand without this safety device. I dislike the idea of advocating bypassing a safety device, but I understand that's sometimes necessary in the real world.
posted by JMOZ at 12:14 PM on March 15, 2010


One other debugging question- previously, if the scooter was on and you put down the sidestand, would it shut the scooter off?
posted by JMOZ at 12:15 PM on March 15, 2010


With the switch removed from its connector, when the key is turned the gas tank needle rises to the appropriate level; this is the same as previously when the switch was in place and the stand was down. I don't know if putting the stand down kills the motor; but the switch disintegrated mid-ride and the engine conked.
posted by waraw at 1:59 PM on March 15, 2010


Are you able to see the colours of the wires to the kickstand switch?

On the Kymco Quannon 125, the kickstand switch has three pins; Up (Yellow/black), Common (green) and Down (Yellow/green). The function of the 'down' output is to light the kickstand warning light.

Do you have access to any sort of multimeter? If so, I suggest you (carefully) probe the three pins on the bike for continuity to 0v (at the battery), or continuity to 12v (at the battery, with the ignition on) and see if the continuity changes when you flick the kill switch on the handlebars.
posted by Mike1024 at 3:04 PM on March 15, 2010


Using speaker wire (which should work fine, right? Better than a paperclip, anyway) I have attempted to connect the middle to left, middle to right, left to right, and left-right-middle together. All of them fail and the engine doesn't move.
posted by waraw at 3:11 PM on March 15, 2010


Oh, and there is no kickstand warning light.
posted by waraw at 3:12 PM on March 15, 2010


I'll borrow a multimeter from work tomorrow and do some probin'.
posted by waraw at 3:16 PM on March 15, 2010


So, this is the wiring diagram for another Cool Sports product, and I suspect it's similar to yours?

Wiring Diagram

If we take it that the kickstand is essentially the same as the start/run switch in the diagram, if I'm reading this right, when the stand is down, it grounds out the remote control box via the ignition, which would keep it from running. When it's up, it provides a ground for the starter switch, allowing the starter to work, and doesn't ground the remote control. Any electrical gurus care to comment?

Now, the diagram shows a "G" wire heading off to ground, and the middle terminal not doing anything. This diagram is for an ATV, so this equivalent to your kickstand is undoubtedly a handlebar switch--the kickstand switch may/probably grounds through the bolt that normally holds it in place rather than a separate wire. However, if there are three wires leading from the switch, one of them should lead to the frame, this is a sign we're on the right track.

Again, if I'm reading the diagram right, the machine would run fine if it could be started, but you can't push start a CVT transmission scoot. So that's out, alas.

You simply want to connect the wire in the switch that goes to the starter switch to ground, if my reading is correct. However, please be careful here. The switch seems to be switching grounds, not power. So grounding any of the leads won't make the wiring unhappy. But if I'm wrong, and it's power, you could be creating a short. Be ready to remove the wire if it gets hot.

Anyway, hope this helps.
posted by maxwelton at 4:11 AM on March 19, 2010


Actually, I realize that a wire to ground from any of the three terminals should make the starter work, I think they're a common bus. (Maybe.)
posted by maxwelton at 4:14 AM on March 19, 2010


Bah, I take that back, it makes no sense. Forget 4:14.
posted by maxwelton at 4:14 AM on March 19, 2010


Thanks Max!

I surrendered and garaged it, where I am assured they can fix or bypass it.
posted by waraw at 4:20 PM on March 19, 2010


Rode it home today.
posted by waraw at 6:42 PM on March 23, 2010


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