Neutral Light Issue

[Zaxeiler]

So, last week, I took my bike out for the first big ride of the spring.  I road for about an hour, topped out at around 85mph, and overall, had a blast.  However, somewhere during the ride, my bike's neutral (and I believe the overdrive) light went out.  When I would come to a stop, I was only placing the bike in neutral from memory.  Otherwise, the bike seemed to be functioning normally.

But...  When my friend and I stopped for a cool drink, I noticed an issue.  I couldn't start my bike in neutral without holding in the clutch.  It's like my bike didn't know it was in neutral.  However, once the engine was started, I could let the clutch out and the bike wouldn't stall or anything.  Other than the process of starting the bike, it functions normally (besides showing neutral with a green light).  The entire console isn't out, because turn signal, brake, oil, and high beam lights are all functioning.  Only the neutral and OD indicator lights are out.

I rode yesterday and it seemed to have come back on at the end of my ride.   While it was working, I could indeed start the bike in neutral with no clutch.  However, after letting it sit and cool down, the light (and starting w/o clutch) is not working again.

So, it seems like there's no mechanical problem with the transmission or anything.  But, there does appear to be some sort of short or problem...  Everything else about starting occurs normally (headlight dims, bike starts, etc.).  But, the light is out, and while it is, the bike doesn't "know" it's in neutral when I try and start her up.

Thoughts, suggestions, experience, need for immediate repair?

Zac

[Zaxeiler]

By the way, I didn't think to mention, but this is on a 1983 NH (CB550SC).

[Custom82Hawk]

sounds like a neutral position indicator switch or something or other is going out.  have to find somebody here with a book who can look it up.

[Laminar]

If you have a multimeter that's capable, check your diode.

[Custom82Hawk]

if you mean LED i think it's more than that since the bike doesn't register it's in neutral since it makes him hold in the clutch when the light is out.  i'd hope honda didn't make the neutral sensor base itself off the neutral LED itself so that if the light burns out you have to hold in the clutch every time to start it (which i always used to do anyway just to be safe)

[Zaxeiler]

So you guys think that Honda made the neutral sensor get information from the neutral light?  If so, I assume it would just be an easy switch of a bulb.

^But something tells me it won't be that easy...

[Laminar]

if you mean LED i think it's more than that since the bike doesn't register it's in neutral since it makes him hold in the clutch when the light is out.  i'd hope honda didn't make the neutral sensor base itself off the neutral LED itself so that if the light burns out you have to hold in the clutch every time to start it (which i always used to do anyway just to be safe)

I meant diode.

[Custom82Hawk]

i don't think that should be the case.  i would hope not anyway.  since bulbs burn out a lot easier than switches, i'd hope they wouldn't base everything off the bulb itself.

I meant diode.

Ok my bad, I know that the LED is a Light Emitting Diode, so I didn't know which one ya meant, since I don't know of another diode myself, but I don't know that model.

[Zaxeiler]

So, I take it you guys would start with a replacement of the clutch diode?

Zac

[Laminar]

i don't think that should be the case.  i would hope not anyway.  since bulbs burn out a lot easier than switches, i'd hope they wouldn't base everything off the bulb itself.

I meant diode.

Ok my bad, I know that the LED is a Light Emitting Diode, so I didn't know which one ya meant, since I don't know of another diode myself, but I don't know that model.

Blocking diodes are extremely common on bikes.

[Laminar]

So, I take it you guys would start with a replacement of the clutch diode?

Zac

Test it, at least. If you following the wiring diagram around, you'll see everything that affects the neutral light - clutch switch, neutral switch, diode, etc. Make sure everything is operating as it should.

Here's the diagram for a '78 CB750. The idea is the same:



The starter switch, when pushed, provides +12V to the starter solenoid. The solenoid is grounded through either the clutch switch or the neutral switch. The neutral switch also grounds the neutral light. If the diode wasn't installed and you pulled the clutch lever in, activating the clutch switch, the neutral light would be grounded and would turn on, that's no good. The diode prevents current from flowing backwards, so the clutch switch can't provide a ground for the neutral light.

These components all affect starting conditions and neutral light operation of the bike, so a problem with starting or neutral light would point towards one of these components as the culprit.

[B83550nighthawk]

The clutch diode is on the right side close to the frame, just above the battery and towards the gas tank. It should have no continuity in one direction between the two tabs, and continuity in the other direction.

[Cmac]

Hey Zaxeiler,

I have this exact problem with my 83 cb550sc.  Have you fixed this problem yet?  Based on the above diagram I have a feeling the culprite is the neutral switch...

If it was the light failing - the bike should still start while its in neutral without holding in the clutch.

If it was the diode failing - the light should still come on when in neutral but the bike won't start without the clutch.

Since the light doesn't come on and the bike won't start in neutral without the clutch, i believe the problem is the neutral switch.

Of course this is assuming only 1 of the 3 components is the problem.  Any combination of 2/3 failures would cause the same situation.

Now since i just bought my bike a month ago, I don't have a manual yet!  Does anyone know where the neutral switch is located??