Topic: Cb400f: Super dim high beam indicator light

[sitz]

I’ve a new-to-me ‘77 CB400f in fine condition though I say so myself. Not showroom, but I’d say easily 90%. The problem I have (if it is a problem) is that the high beam indicator light barely illuminates when flick on the high beams. As in, you can’t see it all unless you pull the lens cover off to reveal the bare bulbs, and then the filament is /barely/ glowing. Swapped the bulbs around and the condition stayed put so it’s not the bulb. I don’t know what “normal” is on these bikes, so I don’t want to devote a bunch of debugging time to it if not necessary.

Thoughts?

Thanks.

[rotortiller]

Light the bulb on a 12v battery and compare, it should be the same in the bike. If not fix the bulb holder or wiring. Check bulb wattage for brightness and voltage as it could be a 24v bulb lol..

[sitz]

The bulb (and to be clear it’s the high beam indicator bulb which is dim, not the headlight itself) checks out fine when I put it in, say, the neutral indicator light socket, so indont think it’s the bulb.

[Flyin900]

You've answered your own question. It is something in the bulb socket or the dual female connection on the inside the headlight bucket. It is an easy trace, as the high beam indicator circuit is a solid dark blue wire off that dual female connector where the solid blue wire for the high beam headlight bulb circuit is connected.
There maybe some corrosion/damage inside the bulb socket itself, or with the male/female connection inside the headlight wiring.
If your high beam headlight is good and bright, it is fed 12V off the same dual female socket noted above, so the issue is likely in the two areas I have previously outlined.

Oh there is also a ground wire on the indicator bulb circuit that could also not be grounding from corrosion, so check both wires off the indicator bulb connection.

[Quattrocilindri]

Are you wearing sunglasses while the Hi-beam headlight is on during the daytime?
If so, that explains it, mostly.
However, the hi-beam indicator light is purposely dim if you ride at night, so that it won't be distracting to your eyes while high beam is on for extended periods of time on poorly illuminated country roads.
 Honda made the blue plastic indicator lens so that to filter more light for this reason. Mine is exactly like that on my 350F.

[The Lone Builder]

May be obvious, maybe not; have you cleaned the blue lens? Made a difference on mine.

[sitz]

The fact that Honda made the lens more opaque on purpose is certainly interesting, but in my case I think it’s the bulb. It’s hard to overstate just how dimly lit it is with the cover assembly off so you’re just looking at the bare bulb. The diligent is *barely* glowing; its as if it were connected to a rheostat and the dial turned *just* enough that you could see the filament was orange.

[Quattrocilindri]

The fact that Honda made the lens more opaque on purpose is certainly interesting, but in my case I think it’s the bulb. It’s hard to overstate just how dimly lit it is with the cover assembly off so you’re just looking at the bare bulb. The diligent is *barely* glowing; its as if it were connected to a rheostat and the dial turned *just* enough that you could see the filament was orange.
[/quote

In that case, the bulb socket must have dirty or corroded contacts. So, time to either clean it with either contact cleaner, or find a way to repair/replace it.

[Floshenbarnical]

Are you wearing sunglasses while the Hi-beam headlight is on during the daytime?
If so, that explains it, mostly.
However, the hi-beam indicator light is purposely dim if you ride at night, so that it won't be distracting to your eyes while high beam is on for extended periods of time on poorly illuminated country roads.
 Honda made the blue plastic indicator lens so that to filter more light for this reason. Mine is exactly like that on my 350F.

That's so interesting. I had the opposite problem with the aftermarket dials on my F2 - the high beam indicator LED is so bright I can't see the road in front of it while riding at night. I solved the problem by taping a very small square of electrical tape on the glass over top of it.

[Flyin900]

The fact that Honda made the lens more opaque on purpose is certainly interesting, but in my case I think it’s the bulb. It’s hard to overstate just how dimly lit it is with the cover assembly off so you’re just looking at the bare bulb. The diligent is *barely* glowing; its as if it were connected to a rheostat and the dial turned *just* enough that you could see the filament was orange.

So did you check the suggested circuits? Since what your explaining is a possible case of either a poor 12V+ connection or a bad ground. I have numerous highly restored CB350F and CB400F's in my collection and they are not showing any signs of your experience. While the blue lens is slightly dimmer than the green neutral lens, it should still be quite visible during daylight.

[sitz]

Haven’t had a chance yet (bike is away atm); hoping to be able to this weekend.

[seanbarney41]

I have seen this problem on a few different sohc4 bikes and no, I don't believe it is caused by the blue lense being darker.  I always assumed it was caused by a dirty switch contact.  Never bothered trying to fix it as something that silly and useless is not going to stop me from happily riding.

[dave500]

plus if your like me i never ride at night and will never need to use high beam,except maybe to flash an errant car driver during the day light hours?dont sweat the small stuff.