Rear Lights problem

[Paul Mc]

Have (as far as I'm aware) one final thing to fix on the XZ (have replaced the spring and sorted the rear light switch a few days ago):

I have rear lights as expected when the lights are turned on. They can be a little tempermental, but once the bulbs are in the correct position they seem to work fine.
But when I brake, one bulb loses the rear light and the brake light does not come on. ???
The other bulb retains the rear light, and the brake light comes on as expected.

I've replaced the (corroded) rear light wiring with some from a breakers yard, but the issue is the same so it's further down the loom (I think) - but reckoned I'd ask here first in case anyone recognises the symptoms.

Cheers,
Paul

[macroars]

Do I understand you right when:
1) bulb A works as it should - all the time
2) bulb B works as it should exempt while braking
3) bulb B looses all light while braking

Since the two bulbs are connected further down the line, the easiest fix might be to cut the wires to bulb B, and connect them to those going to bulb A.

Beyond that, my guess is that the brake light wire are connected to the ground wire, and let the electrons pass that way rather than through the bulb.

UPDATE: The short circuit between brake and ground can also be in the bulb or the socket.
Hence, before cutting anything:
a) switch bulb or replace bulb B.
b) clean out and inspect the socket
Then:
c) cut the brake light wire. What happens to the light?
Still the same?
Then the short circuit is between the connection of the lines and the bulb: You have to rewire from the original split or from the other bulb.
Light on?
You have to clean out or replace the socket.

[Paul Mc]

Do I understand you right when:
1) bulb A works as it should - all the time
2) bulb B works as it should exempt while braking
3) bulb B looses all light while braking

Yep, that's correct.

Since the two bulbs are connected further down the line, the easiest fix might be to cut the wires to bulb B, and connect them to those going to bulb A.

This was my first thought also, as I reckoned that the problem was with the rear section of the loom.
The fact that I found this section at the only local breakers (XZ550's are as common as hen's teeth in the UK) I thought I'd just replace it and job done, but the new (in far better shape) loom is showing the same issue.
I've no problem ripping apart the lesser loom and wiring past the problem - the only thing that concerns me is that perhaps the problem is somewhere else in the loom/near a fuse or other connection or is indicative of a different fault which you chaps might be aware of.
For 2 different rear light loom sections to show the same problem is a little odd in my opinion.

Beyond that, my guess is that the brake light wire are connected to the ground wire, and let the electrons pass that way rather than through the bulb.

UPDATE: The short circuit between brake and ground can also be in the bulb or the socket.
Hence, before cutting anything:
a) switch bulb or replace bulb B.
b) clean out and inspect the socket
Then:
c) cut the brake light wire. What happens to the light?
Still the same?
Then the short circuit is between the connection of the lines and the bulb: You have to rewire from the original split or from the other bulb.
Light on?
You have to clean out or replace the socket.

I've been messing about, swapping bulbs and replacing bulbs (have a few kicking about), and again with replacing the rear loom section I've replaced the bulb holders too.
Bulbs don't appear to be the problem.

I'll re-wire the original rear loom section (and cut the wire as you recommend above - good idea, should give me more info) and that'll get the lights working - just have a niggle at the back of my mind that perhaps something else isn't right (perhaps battery simply hasn't got the power to run all the lights - doubt this, fairly new and showing okay to voltmeter)...

Cheers,
Paul

[macroars]

(perhaps battery simply hasn't got the power to run all the lights - doubt this, fairly new and showing okay to voltmeter)...

Me doubt that too, for then you would loose all light, not only one...

I am pretty sure there is a short circuit with resistance big enough to not blow the fuse, but small enough to make the electrons wander that way and not through the bulb somewhere in the line between the bulb and the connection point.

Does your other lights loose intensity when you brake?

[Kevin]

Poor ground.

[macroars]

Yes! Sounds plausible.

[Paul Mc]

Poor ground.

First thing I did was connect the earth on the problem side to the earth on the good side.
No improvement.  :-\

Was playing about last night with this again, same problem on the original loom (and no other lights dimming when braking) but then managed to get the replacement loom running correctly without interfering with the wiring, so she's up and running at the moment as she should be.  ;)
Still intend re-wiring the original rear light loom section, for a bit more confidence.
Bike will be ready for the MOT shortly (UK Road-worthiness test), assuming I don't find any other problems!

Cheers,
Paul

[YellowJacket!]

I  have an extra set of rear light plugs and wires if you need them.  Just let me know.

David

[h2olawyer]

But David, that's a UK bike.  It probably has one of those positive ground electrical systems that nobody can figure out.   :)

H₂O

[Rick G]

The Brits got over their fixation of running the electrons in reverse , when they  stopped building bikes. the new ones are neg. ground.

[h2olawyer]

My attempt at humour.  A friend had a Lotus Europa I think a 72.  It had a negative ground.  But as a mostly fiberglass car, it had one large ground bole in the lower front trunk area.  (The europa is a mid-engine car.)  Even with lock washers & loctite, that bolt would come loose & all the cockpit electrics would flicker.

That was one hell of a fun car to drive, though.  The pedals are so close together you couldn't wear any wide soled running type shoes to drive it.  With your foot centered on the brake pedal, the soles would push not only the brake, but the clutch & gas as well.  The friend who owned it is 6'4" tall & the roof was below his waist.  I'm only 6 feet tall, but we were told on numerous occasions it was unbelievable to some folks that we could fit in that little car, after they would watch us unfold out of it.  Before he found a replacement front airdam, it would start flying at speeds over 70.  I think it weighed about 1700 pounds.  Top speed was not much over 100, but it would go around corners like a go-kart.

He traded that car straight across for a 67 Shelby GT-500 Mustang.  The dealer was asking a whole $7500 for the Shelby.

Dad owned a Triumph TR-3 in the early 60s.  That car had the positive ground system & he was forever chasing electrical gremlins.  The carbs (strombergs) also refused to stay in synch.  He said when it was running right, it was a real blast to drive.  I remember toddling around the driveway on weekends when he was working on that car.  He taught me "the right words" to use while working on mechanical objects & I was only 3 years old.   ;D  Probably good training for owning a Vision!

H₂O

[Rick G]

I had to learn the right words by myself , my step dad wouldn't say sh*t if he had a  mouthful!

[Paul Mc]

I  have an extra set of rear light plugs and wires if you need them. 

Cheers David, I found spares in a breakers about 5 miles away, they're in and working now.

My attempt at humour.  A friend had a Lotus Europa I think a 72.  It had a negative ground.  But as a mostly fiberglass car, it had one large ground bole in the lower front trunk area.  (The europa is a mid-engine car.)  Even with lock washers & loctite, that bolt would come loose & all the cockpit electrics would flicker.

Older (~late 80s and early 90s) cars, such as UK Ford Sierra had grounds through the frame, getting rusty (UK weather) and then messing up the lights.
Followed a car a few nights ago with my step-daughter, indicated left and all rear lights flashed (rear, brake and reverse as well as indicator) and explained to her the cause - but see it less over here now.

I had to learn the right words by myself , my step dad wouldn't say sh*t if he had a  mouthful!

It's the other way around in our house, I've been trying to teach my little girl (now 15) to swear for years, she's progressed to "damn" and has uttered "crap" once, can't get her to come out with anything stronger - despite listening to an expert (I'm Irish, every other word begins with F, and if I get injured working on a bike I start inventing new ones) for the past 12 years.. :D

Paul

[Brian Moffet]

(I'm Irish, every other word begins with F, and if I get injured working on a bike I start inventing new ones) for the past 12 years.. :D

She probably can't understand your accent  ;D

Brian

[Rick G]

What do you get when you cross an English Ford Consul with an English Ford Cortina? You get a Concertina!!! ;D ;D ;D ;D ;D ;D ;D

[macroars]

Lucas (Prince of Darkness) is the Brit answer to German Bosch, and is also known for its quality. But, in opposition to Bosch; not for good quality. Hence are Lucas jokes standard procedure in every UK-car related discussion....
I.e:
- Lucas dip-switch positions: LOW and BLOW
- Lucas denies having invented darkness. But they still claim "sudden, unexpected darkness"
- Do you know why the Brits are drinking warm beer? Lucas made the refrigerators, too.

[Rick G]

The USAF had some components , in F16s  , that were manufactured by Joseph Lucas , Prince of Darkness. They had major problems with them. It seems that none of them ever rode an old British bike or car and so had no point of reference.

[Paul Mc]

http://www.mez.co.uk/lucas.html

on the Lucas theme -apologies if you've seen it (a hundred times) before...

Paul

[Rick G]

That is really a hoot!!!!! ;D ;D ;D ;D ;D ;D