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reverse safety switch for 2000 honda trx300ex question


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Looking at the schematic, it looks to me like if the switch were to go open/bad, it would break the ground connection to the CDI box? If that were to happen, that would cause a no spark condition Can anyone confirm this? At this time, no spark is my problem and measures 0 volts to the cdi box? Thanks 🙂

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I removed the wire from the switch, and grounded it. There's still no voltage to the ICM/CDI so I assume, there must be an open circuit in that ground wire. I'm going to run a bypass wire in the morning and see if I get spark/start. Hopefully, I can just do that. The reverse lever and cable were not on it anyway when I got it.

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If you are getting no power to CDI there is a fuse and 2 switches to stop power from getting there check from BL/W to battery neg and see if you get power there check continuity from reverse switch connector to CDI . If you said reverse switch is broken just replace it and cable or if you want to get it running first just ground the GR wire. Just my thoughts.

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The one labeled G/W. And yeah, going to the stator housing, that's what that circle is, the dot means there is a connection, and those stacks of short lines all along the bottom of the diagram are the symbol for earth.. so everything that has that earth sign all have to be connected, the engine, frame, battery negative, coil, reverse switch. If the reverse switch and the trigger coil only have one wire then they are earthed internally to the engine.

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Ok, so test from the ICM black/white wire to a good earth on the engine first, and then on the battery's negative terminal, and see if you get 12 volts both places.. with both key and run switches on. If it doesn't get 12v on the engine, but it does on the battery negative, then the engine needs a wire connecting it to the negative. If you can't get 12v on the B/W wire using either earth, then you need to check the fuse and both switches are getting power through them.

If/when you do get 12 volt from the B/W wire using the engine for an earth, but the G/W wire still doesn't work as an earth, then the problem is that the green/white wire isn't getting to earth as it should down on the stator housing..

Edited by Mech
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If you have a test light with a bulb in it, use that looking for the power and the earths.. It can happen that a bad connection is letting a tiny mount of power through, or providing a tiny amount of earth, and that tiny amount of power is enough to make the gauge go, but as soon as the load comes on that bad connection it fails to let enough power through and so it looks dead..  The bulb in the test light draws enough power so we don't get tricked by the bad connection.

The starter needs a good supply and earth so the engine should have either a big earth cable, or the engine is mounted solidly to the frame..

If the starter operates, the engine is earthed.. 

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Good morning folks, I ran bypass wire for ground to CDI box. Well, I'm getting spark now but still no start. The engine for some reason seems to crank a lot faster than before it seemed like it struggled before like it had a lot more to turn over. any ideas what could be going on now?  Thanks! 😒

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Good work so far..

So, it could be that the engine is trying to run and that's why it's sounding fast..  Do you think it's firing at all ? Did it use to go, before the loss of spark ? Have you tried kick starting it ? Did it seem like it had compression ?

Probably you should try to check it has compression. If you don't have a gauge take the spark plug out, put your finger in the spark plug hole and crank the engine over. If you can keep your finger in the hole it doesn't have enough compression. If your finger gets lifted and the air escapes it's probably enough.. depending how tough or woosy your fingers are..haha.


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Ha.. join the club.

In theory we can push start them but without a manual handlebar clutch it's kinda hard.  We'd need to use the shift lever which activates a clutch, or just push till the wheels slid or the engine started turning.  With a big hill, and using the shift lever or decompression lever we can roll start them.  But it should have a kick start, that will show whether it has reasonable compression or not.  Try kicking it.. it should take a bit of effort if it has compression..

Did it use to go before the spark problem ?   You haven't shorted out that reverse switch wire have you ? I think that reverse switch controls the engine power when in reverse. I'm not sure what it actually does, whether it just limits the revs, or whether it retards the ignition timing to lower the power, but it might make it hard to start if the reverse switch is closed.

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It has a handlebar clutch lever is that what you are referring to? no kick start that I can see. After I put the new carb on it started but, cranked slowly like it had a load on it. I pushed it over by my car after it died and wouldn't start and that's when I noticed the effortless fast cranking.

I figured the one way bearing quit catching in either direction but, I'm really not sure how they work.

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