Good Day,

I would like to please humbly ask for some help.

My NC30 VFR has never had working headlights since I got it, last weekend I decided to fix this. I checked and the globes fitted were 60/55w. My NC30 is full jap spec, so it needed 60/35. The previous owner fitted 60/55 and subsequently melted the light switch. it didnt even have the high low beam switch anymore, someone filled it with plastic putty and removed the internals and covered the mess up "neatly". I sourced a decent spare light switch from a scrapyard and replaced only the top half of the switch that was melted and could not find 60/35 globes so I fitted 35/35w in the meantime.

The lights now work in that they come on and off etc. however the flash switch (passing light) still doesnt operate the lights, but I have low and high beam circuits working i think. The bike also has no visible wiring left for the clutch switch. I put it all back together and everything seemed fine. Then all of a sudden it popped the fuse, and the clutch diode started to burn (it made tons of smoke and melted itself) I removed it, checked its continuity as per the haynes manual, and its did not pass the test, so apparently it no longer works.

The bike still started once after this happened, now after that it will not turn the starter motor. Would the failed diode, cause the starter to not engage? Could I simply bridge the diode wires to confirm this? I do not believe the NC30 has a side stand switch, so this is not the problem. Neutral light and all other lights like indicators and breaks still work fine, just seem to have a burnt diode and no starting. Bump start works. Jumping with cables from another battery does not help. it will only start on push start so I think the starter circuit is buggered due to the diode.

MY questions:

• Why would a diode fail in a cloud of smoke out of nowhere - do I have a short to earth somewhere?
  Why would the bike start once, with a failed diode and then never again (are the two related?)
  Can I bridge the diode wires to see if it starts without melting something (this was I can know I need a new diode and not something else that failed causing the diode to burn)

ITs worth noting, the wiring was an absolute mess to begin with, and I did my best to match the new light switch, however perhaps I have made a short in the switch in error, could this cause the diode to fail? Is that possible? I am hesitant to spend alot of money on a new diode, only to fit it, and then watch that one blow up too,

Thanks so much for your time, and any input.

Travis.

If clutch switch wiring is incomplete or faulty and clutch diode not present starter will not function. If diode replaced by short then starter should work when in neutral if other wiring ok, but the neutral light will be constantly ON. If an OEM diode is expensive, then use one from an electronic supply store. Diode failure could have been simply an isolated device failure, which fuse blew? Which exact parts of the clutch switch wiring was missing? If you reside in the UK perhaps you can get a new old loom from someone on this website if you consider the wiring to be too badly damaged.

Your bike should have the OEM highbeam relay and you should do the lowbeam relay mod as described in the document library on the home page of this website. The passing switch wiring may also be missing/ faulty.

Thanks Magg, sincerely appreciate the reply. I did bridge the diode yesterday using two spade connectors on a piece of wire, bike starts right up. The neutral light only comes on when in neutral, I assume the wiring has been modified such that the wires to the clutch switch were cut out. I will attempt to reinstall them. I think the purpose of the diode is to stop the light always going on when the clutch is not pulled so I will have to replace it soon.
I ordered a diode from Honda South Africa (where I am based) and it will arrive in 3 weeks. So the diode missing did cause the starter motor to not operate, fitting the "bridge wire" has overcome this. So I still have some work to do, I will also investigate doing the headlight relay mod so I can use readily available 60/55 globes.

The fuse that blew was the indicator circuit, it still blows the 15amp fuse as soon as I turn the ignition on, I fitted a 20amp and it doesnt. I dont intend to ride the bike until I can figure out if I have a short somewhere as I dont want to ruin the harness (whats left of it)

I wish they still made harnesses id buy one today lol.

Thanks!
T

I would be reluctant to use a 20A fuse as the failure of the 15A is an indication that something is seriously amiss. Indicator fuse covers the indicators, front and rear stop light switches, and numerous instrument lights and units (tacho and speed limiter). If you measure the resistance to frame from the Indicator fuse contact on the loom side, with the fuse removed, and then disconnect the various items in turn you may be able to isolate the cause. If after all items are disconnected the short to frame still exist, then likely a loom fault.

Again, if the loomis in a bad way why not advertise on the forum for a replacement loom.

I will try the suggestions about checking the resistance as described, thanks! Should it be a specific reading? what sort of reading would indicate the fault? The problem I face with buying from someone on the site, is the exchange rate, the cost of shipping and worries about how to facilitate payment. I live in deep dark Africa and everything is more complicated from here..

To blow a 15A fuse at ignition turn-on would require a resistance of less than 1.0 ohm. The lowest resistance would be when the stop lights are on if either the front or rear switches were closed and even then it would be no lower than 3.5 ohms. With all electrical items disconnected resistance should be infinite.

awesome, thanks, Im still learning about electronics and will give this a try, much appreciated.

update: I replaced the Clutch Diode, problem solved. I had a short in the fuse box, repaired, all better. Thanks.