Charging light flickering, now not coming on with main switch on

Supercat

Supercat

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Aug 23, 2017
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Hi there,

I rode my 72 Commando 750 to work today, as I do whenever the weather is decent, and ran into an issue just now. I had to leave the office for an appointment and when I got back to my work parking lot I noticed just before shutting the bike down that the charging light was flickering at idle. I watched it for a minute and then shut the bike off. Then I immediately noticed that the charging light is not coming on when I turn the main switch to on. Lights don't come on in the light position either. Nothing is obviously unhooked at the back of the main switch (but I didn't pull the boot off yet), and the fuse looks to be intact at first glance. Don't have a multi-meter with me to check the battery or anything else.

Not sure if I will be able to ride home after work now or not. I didn't try to start it after this, but it did shut off as normal when I turned the key to off. So I am hoping maybe I can just put it into the on position and try to start it? Or try taking the boot off of the main switch to see if any wires have come off - this doesn't seem likely though as I felt around in there with my fingers.

Two other clues: 1) I did make rare use of the horn on this particular ride (may or may not have anything to do with this); 2) there was a little bit of clattering in the exhaust area as I was getting to the parking lot. I was looking at this when I noticed the charge light, but it just looked like the pipe might be a bit loose and a couple of bolts need tightening. I could see the header and muffler moving a little more than normal on that side. I think that's not likely related, but figured I'd mention it. I didn't touch this before coming back into work as it was very hot. I should probably also mention that its a scorcher outside today. About 30 degrees Celsius, but that's pretty normal at the moment and I've been riding around in heat like that all the time.

Any suggestions? Thanks!

J
 
Supercat said:
Hi there,

I rode my 72 Commando 750 to work today, as I do whenever the weather is decent, and ran into an issue just now. I had to leave the office for an appointment and when I got back to my work parking lot I noticed just before shutting the bike down that the charging light was flickering at idle. I watched it for a minute and then shut the bike off. Then I immediately noticed that the charging light is not coming on when I turn the main switch to on. Lights don't come on in the light position either. Nothing is obviously unhooked at the back of the main switch (but I didn't pull the boot off yet), and the fuse looks to be intact at first glance. Don't have a multi-meter with me to check the battery or anything else.

Not sure if I will be able to ride home after work now or not. I didn't try to start it after this, but it did shut off as normal when I turned the key to off. So I am hoping maybe I can just put it into the on position and try to start it? Or try taking the boot off of the main switch to see if any wires have come off - this doesn't seem likely though as I felt around in there with my fingers.

Two other clues: 1) I did make rare use of the horn on this particular ride (may or may not have anything to do with this); 2) there was a little bit of clattering in the exhaust area as I was getting to the parking lot. I was looking at this when I noticed the charge light, but it just looked like the pipe might be a bit loose and a couple of bolts need tightening. I could see the header and muffler moving a little more than normal on that side. I think that's not likely related, but figured I'd mention it. I didn't touch this before coming back into work as it was very hot. I should probably also mention that its a scorcher outside today. About 30 degrees Celsius, but that's pretty normal at the moment and I've been riding around in heat like that all the time.

Any suggestions? Thanks!

J
Click to expand...
I would be very concerned about a loose header.

You have a loose/bad connection somewhere. If you used the horn more than a few seconds, you could have melted a wire.

Turn the key to on, try the front and rear brake - if the brake light lights, tap the horn button, If it sounds and if the bike will start, then you should be able to ride home. If the brake light works and the horn does not, you may have burned a ground wire or the horn wire. Horn wire is no big deal, ground wire may stop you.

I would not worry much about the charge light. The assimilator simply tells you that the rotor is spinning in the stator and making some AC power - it does not tell you that the battery is charging.

I would not worry about the charge light for a ride home if the above is OK.
 
The fuse holders are rubbish, you could have a good fuse but no contact. If you have a working blue 2MC capacitor then when the fuse blows or stops contacting the bike will still run with lights until you switch the ignition off. Then when you try to turn the bike on you get nothing. So check the fuse and also that the fuse holder is contacting both ends of the fuse. Sometimes you can kick start it just on the capacitor, another way to get the bike going is to bump-start it
 
The exhaust looseness is from the clamp between the header and the muffler. I have a little thumb wrench with me and can sort that out no prob.

No rear brake lights, or regular lights, no horn, and no assimilator light with the key in any position. I do have a working blue flux capacitor. Maybe I blew the fuse with the horn and it looks ok but is shot? It also sounded like something fell out of the fuse holder when I opened it up, but I couldn't see anything on the ground. Might have been my imagination. Should I be doing any experiments with tin foil in the fuse holder? I think I can find some foil here in the office.
 
Oh I also have the innards of a main switch in my backpack and can connect ignition wires using that - but still need a connection in the main fuse area if that's the issue.

Probably worth noting that I did recently rebuild the switch that has the horn button in it. The original aluminum cover got smashed, and I managed to save all the inside bits and to get a new cover. I've used the horn a good few times since then, but maybe vibrations have worn through some insulation or something in that area.
 
Supercat said:
Maybe I blew the fuse with the horn and it looks ok but is shot?
Click to expand...
Had one a these a month ago on a quad, fuse wire was intact in side the fuse but the solder had melted on one end of the wire and the wire was intermittently making contact with the fuse end.
 
Turn ignition on, no lights, put a spark plug on head so you can see if there is a spark, then kick. If the fuse is gone but capacitor is good then you should get a spark even if its every 2 or 3 kicks.
 
Got her going as per kommando's suggestion (thanks again for that!), and made it about half way home. Had some sputtering at stop lights etc. and it was pretty unenjoyable during rush hour traffic. Pulled off at a shopping complex and she cut out as I was idling across the parking lot there. My girlfriend picked me up and I'm gonna head over after supper with some spare fuses, a multi-meter and some tools. Pretty sure the fuse is shot, and I'm guessing it was horn related, but not sure about that. yet And I wonder if the sputtering etc had anything to do with brake light use? It seemed to be ok if I could get the RPMs up a bit.
 
You may have a short in one circuit enough to take the fuse out but not enough to take all the alternator power. What circuit you use that causes the spluttering are the likely short, rear brake light being one as it's on a long wire that gets a lot of water.
 
Switched the fuse and everything works perfectly. Made it home without a hitch, but did not touch the horn :). She's now sleeping soundly in the shed, and I'll have a look at the horn wiring when I get a few minutes. Supposed to rain tonight and tmrw so there will be a bit of down time for that sort of thing. Also, I'm pretty sure my missis thinks I'm particularly cool now because of my mad bike fixing skills ;). She was kind enough to bring me to the lot where the Norton was waiting and the fuse switch took about 5 seconds,, which she seemed very impressed with. Thanks again for all the help and advice!! Much appreciated!
 
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