Lights variating in brightness in time with indicators

[J.M.]

As the title says really.

On the bike, my headlight & taillight dim when the indicators turn on, brighten when they turn off, etc.  They're essentially flashing in time with the indicators. It has never really bothered me as the charging system always keeps the battery topped up to a healthy level, so I have never attempted to fix it. Alternator output is fine, reg/rec output is fine. However my MOT is in a couple of weeks time and this is a failure, so it needs fixing.

I'm lead to believe that these are the symptoms of a bad earth. I'm currently at University, but intend to try and fix this when I get home tonight along with soldering some wires, as my bike is in bits at the moment whilst I'm waiting on new shims to arrive.

Where is/are the earth point/points on this bike? How do I find it/them? How do I check it/them? How do I fix it/them?

Any help is greatly appreciated I'll keep on Googling whilst refreshing this page

J.M.

[adidasguy]

Bad battery and/or voltage regulator.
Perhaps a bigger problem: stator.

Time to get out your volt meter and start checking things.
Do a static stator test. That will tell really quick if it has died.
Then start checking voltages with bike off, bike on and revving at 3k rpm or higher.

Your Haynes or Clymer manuals will walk you through the tests. Also check the WIKI.

GROUND: The entire frame is grounded. Off of the battery negative terminal are 2 wires: one goes to the engine and the other ground goes into the wiring harness. maybe one of those broke? If one did, probably the one to the harness. It is smaller. Without the ground to the engine, you probably wouldn't be able to start it and it wouldn't run well. All lights are grounded through the wiring harness.

[BockinBboy]

I'll put my vote on the battery...



- Bboy

[crzydood17]

Rev the bike to 5000 RPM and see if it still does it...

[jacob92icu]

Hmmmm, I would suspect a little bit of variation to be normal, sort of like how when you accelerate your lights get brighter. I cant think of anything that would be wrong other than a bad ground connection like you were saying. Definitely check the connections and clean them with a wire brush etc... for a better connection.

[adidasguy]

Lights on the GS stay very stable. The battery acts like a huge capacitor. That filters it and keeps it stable along with the voltage regulator.

Check the battery, too.

Did the problem come on suddenly or slowly?

[jacob92icu]

Ya thats true adidas. Maybe the battery has gone bad and its not holding enough charge to keep the lights stable like a good capacitor should. 

[weedahoe]

This isnt a true resolution but something I think you should do anyway,

change all the bulbs to LED

[Bluesmudge]

Uh oh, my bike does this too. I didn't know it meant there was some other problem. I will be watching this thread.

[PatheticPuma]

My old v45 Sabre, was terrible. Spent hours trying to figure it out. In the end I just needed to make a new ground wire from battery to frame. The wires had gotten incredibly corroded near the connections.

[adidasguy]

Uh oh, my bike does this too. I didn't know it meant there was some other problem. I will be watching this thread.

We could check it in the Bike Cave then report back here.

[Higgins13]

Battery

[Janx101]

my bike has always done this a little at idle ... and very very slightly if i hit the brakes and indicate at the same time below errr... 4k rpm? .. ive never worried about it really....

only got a standard wet cell battery though... 

unless it affects visibility or becomes way more pronounced i aint too worried ..

... if something wears out later .. i'll replace it i guess

[J.M.]

Typed a whole long reply to this and lost it

Sorry for the late reply on this post; I spent last night reassembling the bike as my new shims will not arrive until Monday and I've got about 150 mile to do at the weekend.

Some more information:
When I bought the bike it was running at a constant loss. It took me a long time to realise this and I really didn't notice it until I started riding at night for the first time and the backlight brightness (clocks) would variate hugely depending on RPM. I ran the battery flat several times, but still enough juice to bump start.

I replaced the stator, reg/rec and battery and the problem still was there. I left it for quite a while. Coming home once after a 600 mile trip, the bike completely cut out. The battery was 100% dead. Not even the idiot lights would come on.

In the end I fixed the charging problem by wiring the reg/rec directly in to the battery with an inline 20A fuse. I haven't had any charging issues in the 2-3k miles done since.

The bike starts easily and turns over nicely, but the new battery could have been damaged by the above.

But due to the charging issues, it's always happened in my ownership. As I say, I'm not really fussed about it, but it seems that it may be an MOT failure if not sorted.

Ground to the engine is fine. Checked this when the engine was out over Christmas.

Will check the ground to the wiring harness today and see what it's like. I'll also attempt to find the ground to the frame. Harness is my #1 suspect though.

I haven't checked if it does it with revs around 5k. At that RPM I'm riding, so it's eyes on the road! I'll give that a check too and report back!

This bike has cost me a fortune... certainly has taught me what to look out for when buying new bikes!

[J.M.]

Well, haven't a clue what I did specifically, but seems to be working a lot more nicely now.

The wiring harness has been butchered a little bit for fitment of various accessories (which I have removed). I spent the day going over all affected wires, removing the electrical tape, properly soldering them and using heat-shrink to protect them rather than electrical tape. Much neater!

Connections on the indicator relay were a bit corroded, so I cleaned those up. The earth from the battery to the harness seemed okay, but cleaned it up anyway.

Connector block for the main solenoid was in pretty bad shape, so I've removed it. I now have an easily accessible main fuse (seriously, why do they hide these things under the battery/behind fairings?!) and much more secure connections to the solenoid.

Got around 150 miles to do at the weekend, picking up a GSXF600 for a friend, so if I've messed something up I guess I'll find out soon!

[adidasguy]

Seems like there could have been lots of bad connections and maybe even some minor shorts.
Cleaning up butchered wiring is one way to fix things.
Very good that you did that. Those crappy connections could have failed and then you'd be sitting by the side of the road waiting for a tow.

[J.M.]

Yes, I suspect a minor short must have been the cause. Maybe that was also the reason it wasn't charging properly beforehand!

One wire left to go, but it'll be okay for now. There's a wire coming from the ignition barrel which has been spliced for a switched live on the relay. When installing my new shims (probably Wednesday), I'll remove that wire and use heat shrink to protect it. I didn't do it today as it requires tank removal and the fuel hoses are a huge pain!