NC31 FIIr electrical issue

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J053F
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Bike owned: CB400sf NC31 F-IIr
NC31 FIIr electrical issue

Post by J053F » Mon Sep 30, 2013 10:03 pm

First step was the introductions.

My bike is a CB400 NC31.
I bought it 2.5 years ago, and runs smoothly, no issues there.
Since the very beginning I have an issue with my gauge indicators for oil pressure, temp and side stand.

All 3 bulbs do not work at all (as far as I know, they should illuminate when ignition is on, before start the engine).

All other indications (turn, high beam, newtral, alarm, and clocks illumination and gauges (speedo, temp, and rpm) are working fine). Moreover all other electrical functions (lights, brakes, levers, buttons work perfectly well).

Recently I replaced the inner white housing of the gauge, including the lower black part. I used genuine Honda parts, and also kept my speedo, rpm and fuel gauge, which work perfectly.

The reason I did this was because the old ones were damaged and draftly repared with silicone glue from the previous owner. Visually you cannot tell the difference. However under severe rain fall, hymidity could appear below the classes.

Anyway, I had some hopes that replacing the white housing with a new one, including the cirquit for these gauges, I would resolve the problem. Unfortunatelly the problem remains.

I do not think that the sensors of all 3 indicators are not functioning. For example, if I open the sidestand while gear is in, the engine goes out. Therefore, at least this sensor is properly working.
I have also ispected the fuel box. Everything is also ok.

Any ideas what I should check next?

Thank you all in advance.

Gidanski
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Re: NC31 FIIr electrical issue

Post by Gidanski » Tue Oct 01, 2013 5:24 am

Did you check the bulbs whilst you had the gauges apart? Not trying to be a smart arse but that could be your issue. The bulbs ate a T5 wedge globe if you need to grab a few.

Also are both connectors for the clocks connected? there may also be corrosion on the terminals as well. As for the temperature gauge it also has a sensor that can fail as well. It is under the tank on the left hand side (from seated position) with a single wire going to it. there will also be a black ground wire that bolts onto there as well. make sure both connections are clean and free of corrosion.

Apart from that the only other thing I can think of is a blown fuse. Under the left hand side pod there is the fuse box. All the fuses are 10A if I remember correctly. It may just be as simple as that.

Good luck with sorting it out.

J053F
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Re: NC31 FIIr electrical issue

Post by J053F » Tue Oct 01, 2013 9:32 pm

Thanks for the input.

I have excluded the bulbs. When replacing the inner housing, all 3 bulbs were replaced, so I think it is highly unlike that all 3 bulbs of the old and new assembly are not working. Besides, as far as I 'm aware of, these bulbs are hard to be blown.

With regards to the connectors, I can check again, but still I have doubts. While reconnecting to the new housing, they seemed in good shape.

I find interresting the part of this cables below the tank. I 'm sure I noticed the one in position, but on the right side, below the tank, but not sure I found the black corresponding to the ground. I will check this again. Still, checking the wiring of the bike from a manual, I realise that this should be a main ground, so if this is not well secured, further electrical issues should appear.

Finally, all fuses are ok. I have inspected them.

Still open to other suggestions!

Gidanski
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Re: NC31 FIIr electrical issue

Post by Gidanski » Wed Oct 02, 2013 11:11 am

I recently replaced my clocks so I will go look at how it is all wired up. Maybe I can trace the positive feed for the bulbs and find out whats going on. Looking at the Workshop manual the neutral, oil pressure and temp gauge all appear to have the same feed for power. Not sure of the wire colour but will find out.

Gidanski
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Re: NC31 FIIr electrical issue

Post by Gidanski » Wed Oct 02, 2013 11:43 am

Ok, so tracing out the WSM wiring diagram. It is the Black wire with a brown trace. It is responsible for the Dim side of the tail light bulbs, Neutral light, Sidestand switch light, Oil pressure light, Horns, Indicators. I think the gauges wiring may be different as you stated you have a fuel gauge instead of temp gauge. So maybe that may be it?

On my white plug the wiring goes as Follows.

Yellow/ Black trace, Blue/red trace, Yellow/Blue trace
Orange/Blue trace, Cyan/Red trace, Black/Brown trace.
Lock Tab

AFIK its a genuine NC31 1992 model set of clocks. To de pin the connector you can from the pin side put a small flat blade screwdriver above the pin and then pull the wire from the back to release it.

Hope this helps.

J053F
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Re: NC31 FIIr electrical issue

Post by J053F » Thu Oct 03, 2013 9:34 am

Thank you for this information.
I m not sure we have the same gauges, still your suggestion should be applicable.
So if I correctly understand, you propose to make some short of bridging?

Valters
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Re: NC31 FIIr electrical issue

Post by Valters » Mon Oct 07, 2013 11:12 pm

I also have a Honda CB400 F2R. When I bought it, it has also damaged instrument panel, and so on ebay I bought a new one. These three indicator lights (side stand, oil, temperature) are not bulbs, but light emitting diodes (LED). If these 3 indicator lights was not functioning before you change it and after, then the fault is somewhere in the wiring.
You can check the wires with multimeter.

There is an instrument panel wiring diagramm:
Image

1 - speedometer, 2 - backlight of devices (12V, 1.7W), 3 - SIDE STAND indicator, 4 - OIL pressure indicator, 5 - Temperature Indicator, 6 - tachometer, 7 - illumination lamp (12V, 1.7 W), 8, 9 - Fuel Gauge, 10 - an indicator of exceeding the allowed speed (12V, 3.4W), 11 - high beam lights indicator, 12 - neutral indicator, 13 - left turn signal indicator, 14 - right turn signal indicator, 15 - block of indicators, 16 - gauge of the index fuel level, 17 - speed sensor, 18 - module for coolant temperature, 19 - block of indicators, 20 - tachometer module.

The color definition of wires is in russian language but I will write a translation:
Б - White
Ч - Black
Кр - Red
Кч - Brown
Ж - Yellow
С - Blue
3 - Green
Ср - Grey
О - Orange
Бц - Colorless
СЗ - Light green

Hope this helps and good luck.

J053F
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Re: NC31 FIIr electrical issue

Post by J053F » Tue Oct 08, 2013 8:26 pm

Thank you valters.
Much though I browsed the internet, I came up any kind of wiring aside from the one you just provided here.

I see that all 3 gauges are regulated from a signal obtained from a direct wiring to each "bulb" plus signal linked to the module for coolant temperature.
The previous owner of the bike had maden a patent, by including a "manual" swich for the radiator fan, to be on the safe side for the warm days we have in Greece during summer, in case of big traffic and slow moving speed, whereas radiator ventilation may not be adequate.
I should check what kind of interference he did there, as I think he might chopped the wiring which may has affected the 3 gauges.

This should be a reasonal aproach, since aside from these 3 gauges, every other electrical part is perfectly working.

In any case, many thank you for this.

Lancerace
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Re: NC31 FIIr electrical issue

Post by Lancerace » Thu Jul 14, 2016 9:21 pm

Is this the one you have... if yes it is an F2s model

Image

squiddy3000
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Re: NC31 FIIr electrical issue

Post by squiddy3000 » Tue Jun 27, 2017 5:40 am

Does anyone have any advice/experience in swapping out the OEM speedo/tacho for aftermarket ones?

I'm planning on swapping in a mini speedo & tacho, and from what I gather there is a speed limiter (Orange/Blue wire) that needs to be connected to 12V to stop it kicking in?

Is this accurate and/or does anyone have any tips for me?


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