What does a flickering nuetral lightmean?

[Rohls]

Hi,

I have a 1975 R90/6. What does a flickering neutral light indicate? Charging system...? Alternator...? Diode board///? How do I check these things? It just started doing this a little while ago.

Thanks!

[Duane Ausherman]

I would first check the connections at the neutral light switch. Were it to be the alternator or diode board, then you would see this symptom at every electrical load, not just one.

[Major Softie]

Do you mean the light lights up exactly when it is supposed to, but it flickers? If so, connections, as Duane suggests, are the first thing I'd check, just starting at the neutral switch connections. That bad connection can be anywhere in the circuit, including at the switch and between the bulb and the socket. It can also be a dying bulb or a dying switch.

[SteveD]

The switch would be an unusual reason I think. You don't read of many neutral switches dying how you describe. Possible though. You more commonly read of them failing by losing oil tightness and leaking everywhere.

The bulb may be a more likely cause, and an easier check and fix if so. Also check the connections on the bulb insert to the circuit board/bulb holder. They can get rusty (see the dirty tabs on the black bulb holders in the pic...clean 'em up if yours are similar. Also check the copper tang hasn't split where it bends. That's a common spot to lose continuity. A small piece of alum. foil folded and carefully held in position when the bulb is inserted can be an easy fix.
See the bent copper bits...check they're intact.(from a later model this one)


Old cracked wiring is also possible. At the very least, check the switch is well connected. Fiddly spot unfortunately.

[Rohls]

You guys are awesome I'll try it all. And yes, the light functions (turns on once neutral is selected), but flickers constantly.

Thanks!

[SteveD]

This is some of Airbear's fine work..

[Duane Ausherman]

When the light is flickering, have someone watch the light while you fiddle with the wires to the switch. You would hope to see a change, as that area is an easier fix than some others. Actually, access isn't so easy, but at least you are busy with something that you understand. Diagnosing electrical things can be intimidating for many, even though the eventual fix may be simple.

Let us know what you find.

[Seth]

If it flickers all the time, you might look into a bad ground. If the ground it bad, sometimes lights glow as the electricity tries to find another route.

[Jeff in W.C.]

My neutral light used to flicker and it ended up being a bad connection in the big rubber plug to the instrument cluster. Of course there's no quick and easy fix for that. I noticed that if I moved the main wiring harness at the plug, it would affect the neutral light. I ended up hacking into the main plug and installing a bypass wire the since the wiring harness and plug are NLA for the monoshock bikes. They may be still available for earlier bikes, but I don't know.

[Rohls]

Hmmm...so I've checked most connections...I gues my printed circuit board does look a little worn, but the connections are there...and then ridden on my 20 mile/day commute a few times and it still flickers...

I guess i could live with that, but when riding in the dark the other night I noticed the HEADLIGHT DIMS when I apply throttle from ~4000 rpm (When I kinda goose it on the highway)...it does this every time I goose it. What could be causing that? Brushes? Crappy diode board? The battery is good and seems to be charging (never have a problem starting it in the mornings..)...

Ideas?