Honda-SOHC
SOHC.co.uk Forums => CB500/550 => Topic started by: McCabe-Thiele (Ted) on September 10, 2024, 05:50:46 PM
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When I fitted a replacement bulb in my neutral switch panel I thought I saw a slight splash of spark as I fitted the bulb holder back into the Idiot Light Unit mounted on the bars whilst the ignition was still on.
It all works again so thought I would investigate if & why I saw a spark as I fitted the bulb holder back in position.
It occured to me that the live wire to the Neutral bulb lamp must be connected the wrong way round so instead of the center of the bulb holder being live it was the outside. A volt meter test confirmed my suspicions. Does this read as correct?
I have disconnected the two wires in question from the main loom.
One is Black male end (with some odd brown bands on the outer insulation) , the second wire is Female end Light Greenish/Red trace. These two wires had been connected inside the headlamp unit to a Male & Female connector of similar colour. Having done this the oil pressure light has stopped working as it's a shared black connection.
I can just ignore this as once the bulbholder is in position fully home with the rubber cover inside a Plastic holder it's all insulated but it feels wrong somehow.
Has anyone else noticed this arrangement in the Idiot Light Panel?
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Looking at the circuit diagram it appears to show the blacks connected to the centre. But probably nothing to worry about as it should all be encased in the rubber. The indicator warning light changes polarity I think depending on left or right indicators so is also live on the outer at times.
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I've actually cut open the old original bulb holder - oil & neutral ones had black to the outside with the coloured wiring into the center contact caps.
As you say all well insulated once in place.
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Ted, it wouldnt matter which way round it was connected you would still get a spark as 12v goes in on one contact and comes out on the other
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Ted, it wouldnt matter which way round it was connected you would still get a spark as 12v goes in on one contact and comes out on the other
I can't get my head around that - no wonder I'm not much of an electrician. ??? ??? ???
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but do make sure the insulation is in good condition. In the 1980s my friend melted his wiring harness and the short originated in the light cluster in the handlebars. I had to do a lot of chopping out and rewiring to get everything working again. It is a bit of a design weakness having the cluster made of metal; I haven't got mine connected at all.
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Don't be tempted to use a readily available 5w bulb in there, because there's a danger of overheating and melting the plastic warning light unit.
Honda use a 3.4w bulb (part number 34902-259-003) which is the correct and safe fitment.
Hope this helps
Skoti
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No worries on the bulb front, I sourced a new loom with bulb holders and replaced the plastic housing that was melted inside as part of my rebuild.
I've now fitted a replacement LED from the same place as those on my 400 - classiccarleds iirc even lower wattage with nice green illumination that compensates for the faded top lens.
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Don't be tempted to use a readily available 5w bulb in there, because there's a danger of overheating and melting the plastic warning light unit.
Honda use a 3.4w bulb (part number 34902-259-003) which is the correct and safe fitment.
Hope this helps
Skoti
That is a really good point and I bet that's why my friend had trouble.
I do keep toying with the idea of fitting the oil warning light as that does worry me occasionally. Having a lower wattage bulb or LED is a great idea.