Voltmeter inaccuracy


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akinz
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Voltmeter inaccuracy

Post by akinz »

I've been chasing a small electrical problem.

The voltmeter on the bike is showing just over 10 volts.

When the voltage is checked on the red white wire going towards the dash I assume I have 12.3v

I checked the voltage at all the fuses located at the dash and I am getting 10.8v

Does anyone have a clear wiring diagram of the circuit from the main fuse all the way to the fuses? Does the one red white wire carry on to the headlight bucket and then split?

Are there common areas to check where I would be losing the voltage?

Thanks
Kyle

daves79x
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Re: Voltmeter inaccuracy

Post by daves79x »

You are likely losing it at the switch - that is a source of many voltage problems. Take it apart and clean and check the contacts. Other connections also along the way, but I'd go there first.

Dave

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akinz
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Re: Voltmeter inaccuracy

Post by akinz »

Dave, I'm sure you hit the nail on the head.

I didn't see this until this morning, but last night I started at the switch, I could see the red/white wire going into the ignition switch looked like it had gotten hot at one time. I turned the switch on, and happened to wiggle that plug/wire by the ignition switch, I could feel the power wire (red/white) starting to get warm, so I shut it off, took the switch out and unplugged the connector. Cleaned all the connectors put back together and was now getting 12.3V at the fuses, and the voltmeter increased slightly, but still not to 12V.

I'll take a picture tonight, but I noticed one part of the ignition switch casing was broken where the plastic contact clip, clips into the switch housing. Is this a common thing?

Or some ham fisted previous owner broke it?

Anyways, is there a way to take that piece out and clean those contacts?

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Re: Voltmeter inaccuracy

Post by NobleHops »

The voltmeters are known to read roughly 2V lower that you'd measure at the battery. Our noted contributor Aris designed a non-invasive harness to remedy this, if you do a few searches you will find it in short order. Net, don't rely on the voltmeter when troubleshooting for anything more than a better/worse reading.
Nils Menten
Tucson, Arizona, USA '80 CBX, sort-of restored :-)

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Re: Voltmeter inaccuracy

Post by daves79x »

Your one tab is broken off because someone didn't know how to get the base off. You have to turn the key to a certain position for the tabs to release.

Dave

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akinz
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Re: Voltmeter inaccuracy

Post by akinz »

daves79x wrote:Your one tab is broken off because someone didn't know how to get the base off. You have to turn the key to a certain position for the tabs to release.

Dave

And this will enable me to remove the plug portion going into the ignition? What position? And should I have all lights on in 'P' stage of the ignition? I'm only getting the tail light on.

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Re: Voltmeter inaccuracy

Post by daves79x »

P is just the tail light. You just have to fiddle with it, but there is a key position that allow you to depress both tabs easily and completely for removal of the bottom. Easy to see once it's apart, but that doesn't help now. Don't think it's in the shop manual. You should consider getting a new base.

Dave

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Re: Voltmeter inaccuracy

Post by steve murdoch icoa #5322 »

On my '81 the key has to be in the Acc. position for the ignition base removal.

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akinz
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Re: Voltmeter inaccuracy

Post by akinz »

Are the switch bases still available?

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Re: Voltmeter inaccuracy

Post by tevan »

I don't think from Honda but aftermarket ones are out there. Emgo is one brand.

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