Brake light doesn't work from front brake, works from rear.

[BananaLover]

When the front brake is pressed brake light doesn't come on when pedal for the rear brake is pressed light does come on. According to my manual, I needed to test the voltage to locate the problem. There's a 6 pin connector for lights going into the fender that can be disconnected, that's where I measured the voltage coming from the yellow wire, and voltage does come though both, when rear and when the front brakes are activated. So I assumed the issue must be on the fender side. However, by default, there's voltage coming through already, which according to my someone I asked is a problem.

My battery was at 11.2v at the time of testing because I was messing with the lights for too long. The constant current was 7.8v without brakes applied. With either brake applied it went up to 10.8v.
Note that I just replaced the rear bulb also.

What's going on here? Where do I look? I'm kind of a novice so go into detail if you can. Thank you!

Edit: Bike is Yamaha Dragstar XVS650
Also might be relevant that my bike was sitting for a few months without any use.

[Easy-X]

Does help if you mention the make, model & year of the bike!

Always start simple: one brake light, two switches and some wiring. If the rear switch works as expected the first thing to check would be the front switch

Do a resistance check on that switch and see if it's even working.
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Royal Enfield Continental GT 535, Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[Polarbear]

Front brake is usually a pressure switch or a mechanical switch in the lever.

As said, what bike is quite useful when fault finding.
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Triumph Trophy Launch Edition

[Teflon-Mike]

Before faffing with a multi-meter..personally I would have a look at the front brake lever.... as said theres usually a micro-switch behind the lever blade that is 'pressed for off'. So when you pull in the brake lever the plunger pops out the switch and turns 'on' the brake lamp....
2 things, first is the two wires on the switch may come loose, esp if you use a brakle-lock opr have just cleaned the bike or replaced grips or woprse, dropped it, or scraped it up the side of the house wall etc... Check the wires are there and making contact... pull back the condoms and touch the spades together to by-pass the switch... brake lamp should come on.
Next, does the switch plunger pop out? Crack betwen lever blade and bracket where switch sits is notoriouse crud trap, clean carefully, and add lube to make sure switch is switchin when lever pulled... switches can and do go sticky over time, and lever blades get bent and switches get sloppy on the mounts. Look carefully, twiddle the mounting screws, mess with the lever, when you clean, and see if it works better.
Should be obvious when you look, and fiddle... no muylti-meter or wiring diagram required... just patience, a tooth brush, a tooth pick, and some deturgent! Maybe a bit of 3in1....
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My Webby'Tef's-tQ, loads of stuff about my bikes, my Land-Rovers, and the stuff I do with them!
Current Bikes:'Honda VF1000F' ;'CB750F2N' ;'CB125TD ( 6 3 of em!)'; 'Montesa Cota 248'. Learner FAQ's:= 'U want to Ride a Motorbike! Where Do U start?'

[Nobby the Bastard]

[BananaLover]

[WD Forte]

How it works
Basically:
You have a wire going to the brake light element in the rear light (35)
which is grounded locally along with other tail bulbs.
Both front and rear brake light switches can apply voltage to that wire
so one, the other, or both can light up the bulb.

Some/many have spring loaded front brake switches have contacts held open until
the lever moves away from it when pulled.
This allows the contacts to close thereby applying voltage to the brake light bulb.
Some may have a pressure switch on the hydraulic part which essentially does the same.

Testing is pretty simple
Get a meter
Test for power to the switch on the Brown wire
and power out when in use on the Green/yellow
No power in, check wiring
No power out, bad or ill positioned switch

Heres a diagram which may help
Item 45 is the one you want
https://4.bp.blogspot.com/-58pKoLsJbc8/VTT9t8vCqFI/AAAAAAAACME/aUGv6rzShls/s1600/yamaha-dragstar-xvs650-2000.jpg
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bikers smell of wee

[colink98]

[ThatDippyTwat]

[WD Forte]

[BananaLover]

Solved!
So, there was continuity between the pins for the relay but I still tried connecting the pins directly as suggested by Teff, and the light came on. So I tried squeezing the wires deeper on the pins and it worked for half a minute and they slid back down. In other words, they are not holding on to the pins for some reason (was fine for like 3 years I've owned the bike). Or maybe they are too corroded, actually.

Thanks for the help, all the replies taught me something anyway.
I only have one question. There was voltage going through the yellow wire, the same voltage as when the rear brake is pressed. Why? I tested that because the manual said so, why the hell would there be power going to the taillight but it didn't wouldn't work? Also, is the constant current through the yellow wire a problem?
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YAMAHA XVS650 DRAGSTAR 1999

[Chuffin Nora]

[Easy-X]