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-   -   Headlight problems, related to clutch? (https://www.vn750.com/forum/19-electrical/97409-headlight-problems-related-clutch.html)

wmdaricthompson 08-28-2017 02:35 AM

Headlight problems, related to clutch?
Alright fellers, I've got another head scratcher for you. (At least it's a head scratcher to me, I'm hoping someone here knows what is going on right away and can tell me)

After I got my cylinder flooding issue taken care of, I took my bike out for a number of rides. I've cumulatively been out for about 160 miles on it now. (50 miles, 50 miles, 30 miles, 30 miles) It's running smooth and pretty and powerful.

I was feeling cocky so I took it to work today. I'm on the afternoon shift at the moment, so 2-10 pm. As I was pulling out of the plant parking lot on the way home, I put on my turn signal and my headlight flickered, then went out. I reached forward and knocked on the housing, flicked from high to low and back a few times. Nothing. I pull in the clutch to pull over, and BAM. Headlight back on. I continue on. No sooner have I let out the clutch then then light flickers and goes out again. All other lights seem to be working normally. Gauge lights, turn signals, running lights. No issues. I can't tell on tail light, no ready way to observe it. I end up driving 7-8 miles of twisty back roads with only my running lights and the stars to show me the way. Scared me to death, but I wasn't about to stop on the side of a country road without a shoulder at that time of the night. Made it back to civilization (but not home yet, just to a parking lot I could pull into). I got off, checked out my everything I could on the side of the road, and it seemed to be working normally. High beam, low beam, with the bike running on the centerstand in neutral, everything was normal. I take off again, same thing.

One thing I do notice is that the headlight reliably comes on if I pull in the clutch. I make it home carefully accelerating so I can roll past known police camp spots at the speed limit with the clutch pulled in (Went past 2 police stations, and at least 2 officers like this, thankfully no one noticed). Every once in a while, the headlight will stay on for an extended time even with the clutch out. This happened between 3-4k rpm, but that might just have been due to that being my cruising speed. At the end of my thirty mile ride (can I rule out charging system? I feel like it shouldn't have gotten me home if my stator was toast), I thankfully pull into my garage and realize there's not a lot I can do at this time of the night since most tests have the bike running and at elevated RPMs, and I really don't want my neighbors to hate me. I pulled the headlight and find nothing that screams "I AM WRONG" at me save for one spot on the ground wire to the headlight (ground is bl/Y, right?) that has insulation stripped off, but has been pretty adequately electrical taped. No issues with continuity at that spot either. I restarted the bike one last time (centerstand, neutral) and the headlight operated 100% normally. I hung up my screwdriver and multi-meter for the night, and came inside. To me this screams ground problem, but I can't tell where, and the consistent behavior with the clutch seems to contraindicate that.

So, to recap:

1) Bike has no issues with staying running, or with power at any RPM
2) Headlight cuts out unless clutch is pulled in or bike is in neutral, sometimes stays on if in gear with clutch out
3) No other electrics appear to be affected
4) Nothing in the headlight bucket jumped out as being to blame
5) Gonna ride my XJ to work tomorrow instead
6) Our townies aren't very good at paying attention, bless their souls and protect them
7) I am scratching my head on this one. Any electrical gurus out there?

TonyO 08-28-2017 09:41 AM

The only place that all comes together is the infamous Junction Box, sounds like a short between the starter solenoid logic and the headlight relay.

Spockster 08-28-2017 10:29 AM

I was also thinking the headlight relay may be a problem. Could try the Blue wire mod and see what happens. It's not too hard to do and easily changed back if needed.

Did you happen to notice if the white 'headlight' indicator light was lit at any time? That would mean the RLU has activated.

wmdaricthompson 08-28-2017 11:27 AM

I went ahead and did the blue wire mod. I'll still take my XJ to work tonight instead, but I'll take the Vulcan out when I get home to see if it helped. No way I can see the headlight while riding during daylight.

The RLU light never lit while riding, but the circuit is functioning as it lit up when I was troubleshooting and had the headlight off.

It looks like someone, probably the previous owner (man that guy is the worst) had been messing with the junction box already. Everything seemed to be in the right place, but I had to pull a spade connector from the empty spot on the harness. No clue what that was doing there.

Thorn 08-28-2017 02:04 PM

That's crazy.
I'm inclined to agree with Tony that there's a short somewhere between the starter circuit and the headlight circuit.

For what it's worth, with the blue-wire mod in place, the headlight should come on without starting your engine. The short would kill the headlight by pulling the clutch or probably even just having the bike in neutral. Check that the light is stable across the full range of the handlebar rotation.

Blue wire mod will solve the problem if the short is in the junction box, but not if the short is in the harness.
I don't see a lot of short circuits on a circuit boards though ... blown compenents and broken traces, yes, but those wouldn't cause your scenario. Interested to hear the results of the mod.

michiganteddybear 08-28-2017 02:56 PM

im gonna go out on a limb here..

ign switch.

I have seen it do the strangest things. even to me, I had mine cause no turns (but everything else was good)

wmdaricthompson 08-28-2017 03:47 PM

I'll make sure I look at both ignition and kill switches if the blue wire mod shows me no love. I once had a faulty kill switch making bad contact act just like a dead battery except for the fact that I couldn't pop the clutch and start it that way (except it let me do that once).

ubertalldude 08-28-2017 05:11 PM

Goofyfoot will pop in any second now and retell the tale of how his ignition switch damn near killed him...

OleDirtyDoc 08-28-2017 06:31 PM


Originally Posted by ubertalldude (Post 1213841)
Goofyfoot will pop in any second now and retell the tale of how his ignition switch damn near killed him...

nah,he's too busy playing with his new shade of nailpolish

Sent from my LGL34C using Tapatalk

wmdaricthompson 08-29-2017 12:52 AM

Well, for now looks like Blue Wire mod did the trick. After I got home from work I hopped from one saddle to the other and set out. I went to the next town over via residential roads and back on the highway and it didn't cut out once. Total distance of just over four miles. The bike had no problem starting with the headlight on, so I think I'm prepared to call that fixed. My toasted headlight relay can stay toasted. I'm just going to leave it bypassed.

Thanks for saving me a lot of time and trouble getting that ironed out! I'll resurrect this thread if it turns out it wasn't fixed after all and I celebrated prematurely.

I mean, if I survive finding that out anyway.

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