odd behavior of neutral light

so im fairly convinced i still have a few electrical bugs to sort out.. one which is very odd.. maybe someone has seen this and has some ideas..

So when im in gear the neutral light goes out like its supposed to.. however sometimes (not always) when im moving in gear the neutral light will be dimly lit, and then when I roll on throttle the neutral light flickers brightly at a pace that matches engine rpm. Roll off the throttle (while still maintaining speed) and the flickering stops and neutral light goes back to being dimly lit.

Sometimes it doesnt do this at all, but when it does it while driving at night its quite annoying.

The only other thing i should maybe mention is I think my canceling unit stops working when the neutral light is behaving this way.. maybe its just a coincidence

assuming its some kind of short or ground fault.. but looking at the diagram i dont get how engine RPM could cause the neutral light to flicker.

Maybe I'll hook up the gopro tonight to catch a video of what im talking about...

ideas??

thanks

 

Sounds like some kinda grounding, shorting, or cross-feeding issue..... do you have an electronic or manual tach?

 

The issue would almost certainly be a hot-lead -to-the-light issue. The ground is simply a common ground. The switch itself doesn't appear to be the issue, as there's no indication that the bike is cutting out when the light flickers.

If the bike keeps running smoothly and just the light flickers, then it seems pretty clear to me that it would be a bare spot on the + wire to the light is picking up current from another + source...............

Could be wrong. I remember another time I thought I was wrong..........

Dave F

 

Well your neutral light shouldn't be lit at all when you aren't in neutral, so I'd be looking for the wiring from the switch.

As for once a revolution, each coil fires once per revolution. That high voltage current could be getting to that wire (and others), but maybe the load keeps it from blowing up?

Also, your rotor alternator is spinning at a rate relative to your RPM, meaning that when you accelerate, your Rectifier Regulator is having to change the duty cycle of the voltage on the stator to regulate the charging system voltage. So it should be lagging, and would catch up as you roll off the throttle. So there's a small voltage on that bulb when there shouldn't be, it would increase when accelerating.

How bright does the neutral light get when accelerating? As bright as it does when in neutral (12V)?

You'll want to use a multimeter to do voltage drop testing. If you can find a spot on that circuit that has any voltage when it shouldn't (i.e. put the bike in gear, key on, engine off, do you get the neutral light dimly lit? Disconnect the neutral switch, etc), and then trace back from there to find the fault.

How long have you had this bike? How many miles? Did the PO hack up the harness at all? Have you done much electrical work on the bike? 30 y/o connectors corrode bad, but most of the wiring under the insulation is still good if the insulation hasn't failed.

I've personally gone two routes with my XJs, my Seca got all of it's connectors cleaned with contact cleaner and dielectric grease. Any issues that needed to be sorted out were done with whatever they sold at autozone or home depot. The Turbo Seca's harness was fully cleaned, I even depinned male pins and scrubbed the corrosion off, and at the first sign of any voltage drop, I'll install new pins on the circuit with the proper crimping tools. The Turbo Seca's electrical has been performing very well, the Seca still has more issues to trouble shoot 3 years later.

Be prepared to do the electrical right, and spend good money on the tools and connectors (a little over $100 total of the sets I bought here: http://www.vintageconnections.com/ , Professional Kit CK-1 and Professional Kit CK-4, plus a really good wire stripper) and but it is WELL worth it.

 

Not sure what you mean by lagging, but as i roll off its brightness drops immediately, to a dim flicker

Exactly this, yes.

Just as bright, although its flickering -- opposed to being solidly lit, as when in neutral.

will need to do some tear down to get a full voltage drop test and will post results, but here's what i can tell you now.

bike in gear, key on, engine off = not lit at all
bike in neutral, key on, engine off = solid lit
bike in gear, engine idling, stopped = dim flickering in sync with engine rpm
bike in neutral, engine idling, stopped = solid lit
bike in gear, throttle rolled on, accelerating = bright flickering in sync engine rpm -- its as bright as when in neutral
bike in gear, throttle rolled off, coasting or engine braking = dim flickering in engine rpm

if i burp the throttle, quick on, quick off, without adding more than 1mph the light flickers brightly for that brief moment and drops to dim flickering immediately once rolled off.

Its brightly flickering any time the engine is making power.. shouldnt the alternator always producing X current for Y rpm regardless if the throttle is open or closed? I tinker, but EE is not my speciality by a long shot.. :/

bike is 82 maxim with ~37-38k miles have had it since July 2013. Tach is electric. The PO had some poor poor wiring at the harness, etc which i cleaned up w a modern bladed fusebox cleaned up some rats nest in the headlight can, rewired the tail light (see my other posts for service log and photos) but its been doing this flickering thing on and off since i first got the bike.

Thanks all for the insight and for anything anyone else can add.

 

[quote="slackard]Its brightly flickering any time the engine is making power.. shouldnt the alternator always producing X current for Y rpm regardless if the throttle is open or closed? I tinker, but EE is not my speciality by a long shot.. :/[/quote]

What you describe is how a permanent magnet generator works. These alternators are actually The Field Controlled Generators, which actual vary the input current according to the energy demand http://www.electrosport.com/technical-r ... stem-works. So it should produce a steady current to support the load, however, given a constant rotor voltage, more current will be produced from the stator as rpms increase. The RR needs to detect that that change and cycle the rotor current off, so I think you could produce slightly more voltage as the RR lags behind the increase in rpm.

I'd look for a frayed wire or short from the stator or hot wire (brown) in general, near your neutral light circuit, maybe even relays? The 3 white wires off of the stator carry 50V 3-phase a/c, but I'm not sure if they come close to that circuit.

How is your charging system output?

 

I had the exact symptoms you described...I found bare spots on the wiring to the neutral switch that was grounding to the frame. I believe the flickering that matches engine speed is actually caused by the wire being pinched against the frame. As you accelerate, it puts more force on the pinch creating better contact thus getting brighter.

Check the wiring at your neutral switch...see if there's any bare spots, especially where it runs between the engine and frame.

 

from what i can tell its good,.. engine idling, checking voltage at the headlight relay (red/yellow and blue/black) seeing +15v..

curious though, the white wire on the relay, coming from the diode block measures +7v. Is this normal? maybe thats voltage drop through the coil?

im sure there is better way to check charging... guidance??

 

I'm not much of an electrical guy... but go for the obvious easy stuff and retrace your steps first.

1. you said you replaced the fuse box and cleaned up the rats nest in the headlight. - check your work

2. going back to the rats nest, examine everything for loose connectors, cracked/frayed/stripped wires, even uncovered plugs that could be making contact.

more often than not... it's an easy fix....

 

To check the charging system.
1. Fully charge the battery
2. With the motorcycle running, rev to 2500 rpm. Check the voltage at the battery terminals
3. Rev to 5500 rpm. Check the voltage
4. Your readings should be between 14.3 and 14.8 V.

jmilliken is right too. When I said neutral light circuit, I meant everything from the switch (which comes out of the engine I think, so you'd check the wiring), to any relays that use the switch, all the way up to the headlight bucket, and the connectors in there that feed into the gauges. You could have pinched a wire in the headlight bucket.

Voltage drop testing can help you narrow down the problem location. Sometimes a bad connector or frayed insulation isn't immediately obvious, and there's a lot of wire and connectors between that switch and the light bulb in the dash.