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Mystery short - ignition switch?

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Barry View Drop Down
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    Posted: 02 Sep 2018 at 09:40
Electrics are a mystery to me, be gentle! This is an 1000SP, in roadster trim, which has been running fine for many years. Totally reliable, apart from that one time with the loose connection on one of the coils.

The question is this - is it possible that the ignition switch is itself a source of an electrical problem - (which I'd describe as a mystery short)?

I'll be going over the loom *again* today, looking for glaringly loose connections, melted wires, and so on, but in essence:  turn the ignition on, all the lights on the console illuminate. Attempt to turn on a light (main beam, front or rear brake, flasher) and everything turns off. Ignition on, off, on off, no lights, on off, on off - and there they are, all illuminated again. The bike starts and runs, in this state. It's just the lighting circuit, apparently. I discovered it *whilst* the bike was running, and the gen light came on whenever I braked. Wasn't happening when I started off, having done all the usual brake light and indicator checks. 

Battery is tired - it's a few years old, but if it's starting the engine, that shouldn't be the culprit re: the lights, right?

No blown bulbs, no recent changes. Fuses all good and not blowing. So, the electric-naive in me says, it's a 'short' (bad connection, worn wire, cruddy earth) - you just have to find it.  But the fact that the ignition switch fails to 'switch on' intermittently makes me wonder if that switch, in itself, might be the problem (or part of the problem).  The one other potential culprit that I keep looking at out of the corner of my eye, is the front brake (pressure) switch, which (on mine) is located on the outlet from the front master cylinder. I might try disconnecting that today, and see if taking it out of the equation makes a difference.

Anyone able to knowledgeably tell me if it could be? Or if I'm barking up the wrong circuit?
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jpc View Drop Down
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Post Options Post Options   Thanks (1) Thanks(1)   Quote jpc Quote  Post ReplyReply Direct Link To This Post Posted: 02 Sep 2018 at 10:50
The symptoms ring a bell with me, especially the gen light coming on whenever some drain is applied (like the brake light). The rectifier cell has its own separate ground connection, have you checked that ?
Medium big black wire exiting the cell, on the T3 goes to the frame together with the rear light ground wire on the frame crosspiece under center of seat.
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Post Options Post Options   Thanks (1) Thanks(1)   Quote Ken-Guzzibear Quote  Post ReplyReply Direct Link To This Post Posted: 02 Sep 2018 at 10:50
in a word yes it can fil a Zadi one is same the pressure switch is unlikely at left side front end of the tank is a bundle of earths that are all bolted to the frame tank off take a look see not easy to see but there are affair few there ...the other culprit for these type of faults are the 12 n 15 way molex into headlamp ok for years then play up contact cleaner and I put a smear of silicon on edges to seal them
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Post Options Post Options   Thanks (1) Thanks(1)   Quote theone&onlymin Quote  Post ReplyReply Direct Link To This Post Posted: 02 Sep 2018 at 14:21
If you ..

Cheers
Min


Edited by theone&onlymin - 03 Sep 2018 at 09:57
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Brian UK View Drop Down
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Post Options Post Options   Thanks (1) Thanks(1)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 02 Sep 2018 at 14:57
Those symptoms sound more like a dodgy earth somewhere to me. Worth checking them all.
Brian.

Better 5 minutes late in this world than years early in the next.
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Barry View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Barry Quote  Post ReplyReply Direct Link To This Post Posted: 02 Sep 2018 at 18:58
Sincerely appreciate the pointers, chaps. Thank you all. Always handy to have a 'second pair of eyes' with this sort of thing.

Today was too nice to be swearing at electrickery. Went and picked up the spare Zadi ignition switch I had in a box at the back of a dark barn. Then watched the F1 GP in my local, over a couple of glasses of cold stuff. Cooked a nice bit of fish, drank some wine, and enjoyed what might be the last warm days of this wonderful summer. Back to the electrics tomorrow, and I'll report back.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 02 Sep 2018 at 21:48
Glad to see you have your priorities right.

Brian.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Jools Quote  Post ReplyReply Direct Link To This Post Posted: 11 Sep 2018 at 18:14
Went touring 20 years ago with a mate of mine on his V50 (me Trident-mounted in those days). On the second day, the V50 wouldn't fire, despite the engine cranking merrily and all the rest of the electrics working perfectly. It stumped us, but the RAC man discovered that the problem lay within the ignition switch itself.

It was hot-wired to bypass the ignition switch from then on and performed faultlessly thereafter!
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Mike H View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mike H Quote  Post ReplyReply Direct Link To This Post Posted: 11 Sep 2018 at 19:33
That happened to a mate's V50 years ago we were going with a group to Switzerland, an electrician was among us so bodged it up with two wires poking out from under the seat, twist together to turn the bike on, untwist to turn off. Worked therafter for all the remainder of the trip.

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Post Options Post Options   Thanks (1) Thanks(1)   Quote Gianni Quote  Post ReplyReply Direct Link To This Post Posted: 11 Sep 2018 at 20:12
Ah this one...
 
I have had this one my LM, my Spada and my Cali. The gen light when braking is the dead give away - the gen light is illuminated by a bridging circuit rather than to earth and applying the brake sort-of reverses the current flow through the bulb. Auto-electrical engineers please ignore that awfully clumsy and simplified explanation :)
 
The current draw sort of overloads the fuse contact to the red/black wire (fuse 3) which powers both the lighting circuit and the dashboard lights (including one side of the gen light). Sometimes it is the blue wire also (fuse 1) which supplies the front brake light switch which overloads. The fuse(s) will look good and will measure continuity but under load it/they fail to pass current.
 
Test this by removing the fuse box cover. Switch the ignition on and try and reproduce the fault, usually by applying the front brake when the lights are on. Squeeze fuses 1 and 3 end-to-end and the fault should go away.
 
Solution is a good clean on all the fuse box contacts and a new set of fuses.
Le Mans 1, Spada, Cali 1, T3 Mongrel, Le Mans V, Quota x 2, Stelvio TT
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Post Options Post Options   Thanks (0) Thanks(0)   Quote rapheal Quote  Post ReplyReply Direct Link To This Post Posted: 11 Sep 2018 at 22:24
You need to buy a new motorcycle
its Guzzis way of keeping Italians employed

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Barry View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Barry Quote  Post ReplyReply Direct Link To This Post Posted: 12 Sep 2018 at 12:33
Well, now. What can I say?   Long story short, thank you Gianni!

Thank you all for your suggestions - all useful, all sensible, and all noted (except for the comment about getting another Guzzi, because - as we all know - all that does is give you more things you need to fix, rather than something else to ride).

Took notes, missed a week due to Life Happening, but did get around to finding my spare ignition switch, a handful of fuses, and a spare indicator relay (because the indicators were grumbling). Whipped the cover off the bike today and set about it, notes to hand.

First things first, despite having had a look at the fuses quite early on in the proceedings, but because it was as good a place as any to start again - and because Mr. Gianni seemed to describe the *exact* scenario I was seeing, and!  Voila!  or should I say Ecco!

Squeezed Fuse #1 as Gianni suggested, and that basically seems to have done the job. Whipped out all the fuses for good measure (all 16amp, which seems to be correct for a 1000SP?), cleaned up the contacts, and all is looking good.

I've been sceptically turning the ignition on and off every few minutes for the past hour, coffee cup in hand, and dabbing the brakes, turning the lights on and off. No further fails. Perhaps it's me, but I never expect an electrical fix to be "as easy as that"  (o: 

Thanks all!
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Gianni View Drop Down
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Post Options Post Options   Thanks (1) Thanks(1)   Quote Gianni Quote  Post ReplyReply Direct Link To This Post Posted: 12 Sep 2018 at 14:25
Barry, glad I could share my experience and help.
 
Beware that the squeezing solution is somewhat temporary. A full clean of all the contacts, and remove and replace the female spade connectors is more permanent.
Le Mans 1, Spada, Cali 1, T3 Mongrel, Le Mans V, Quota x 2, Stelvio TT
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Post Options Post Options   Thanks (1) Thanks(1)   Quote theone&onlymin Quote  Post ReplyReply Direct Link To This Post Posted: 12 Sep 2018 at 16:09
Squeezing the contacts is good way to go. Sometimes just rotating the fuse a few times cleans up both fuse and contact.
If you want to go crazy you could remove the fuse box and clean up all the contacts hidden behind. Some folks replace the fuse box with something more modern. Not me sir.

Cheers
Min
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Post Options Post Options   Thanks (1) Thanks(1)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 12 Sep 2018 at 16:43
Those conical end fuses are notorious for making a poor contact over time.
Brian.

Better 5 minutes late in this world than years early in the next.
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