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Blowing 20 amp main fuse
- Thread starter Shipper
- Start date
Shipper
XS650 Addict
Alright, really don’t know if I checked this earlier but the bike did run with the headlight on albeit only for 5 to ten minutes. Now I’ll blow a twenty with the key on, bike not running and switch on the headlight. Going to take it for a ride after dinner w/o headlights on. May even disconnect rear light and see what happens. Getting seriously low on 20A fuses so probably have to wait until tomorrow past that.
If you're saying it's now a hard fault... that's a good thing.
Here's what I do to not burn up a ton of fusses. Disconnect everything that you suspect (my post above). Now, turn power back on and make sure the fuse doesn't blow.
Now, start hooking stuff back up until the fuse blows again.... there's where the short is.
Well, it seems you've isolated the problem to the lighting circuit. The tail light is a definite suspect. The wiring to it passes through several grommets and runs under the rear fender for a bit, exposed to all the elements and crap the rear wheel can throw at it. Don't rule out that right switch assembly either. Have you ever gone through it and cleaned and lubed it all up? I recently did a '77 one for use on my '83. It wasn't too bad inside but was a bit crusty .....
A proper cleaning and reassembly with the right greases in the right spots had it good as new again .....
A proper cleaning and reassembly with the right greases in the right spots had it good as new again .....
Yes to that
Dont go on a road trip if the fault is there standing still.
The ride can shift fex a loose cables position.
Try to localize it first.
The other things can come later if needed. ( Ride and Fuse )
Dont go on a road trip if the fault is there standing still.
The ride can shift fex a loose cables position.
Try to localize it first.
The other things can come later if needed. ( Ride and Fuse )
Shipper
XS650 Addict
Fantastic guys. Not sure yet I’ve totally isolated but a long way down the road from a couple days ago. One of you was saying that subsequent consumers may still be culprit but I really think headlights/lights are the source. Cant say thanks enough. Going to dark ride after dinner (still plenty of light outside) and see what happens. Will update.
Cheers
Cheers
Just to emphasize what Jan P just said above.... Don't even think about going for a friggin ride!!
You now have a hard fault. Count yourself lucky it's there and don't move the bike. As Jan just said, you might disturb it and make the hard fault go away. Then you're back to square one. A bird in hand and all that. Hunt for it while it's still there.
Shipper
XS650 Addict
Got it. No ride. I’ll work with what I got. Thanks for the wisdom.
itschrisb
XS650 Addict
Have you considered pulling the whole harness off and looking over the entire thing front to back? It really isn’t all that difficult to remove and unwrap. I just did this on my ‘79.
Hi
Not sure where we are .
Perhaps it is fixed
Or sure of your competence with a wiring diagram
Some hints
If you still are in the position of "Hard Fault " as Jim calls it
There is a fair possibility to remove the battery
And have the fuse there.
The fuse burns because the + connects to - ( bare with me if this oversimplified )
So if you take out the battery and hook up your Voltmeter. There Clamp it with something or hold it .There should be resistance. Switches off.
Now you can turn lock push buttons and watch the resistance meter
Ignition On --and then the dodgy Light switch.
And so on
( Again bare with me if this oversimplified )
At the Schematic
https://thexscafedotcom.files.wordpress.com/2012/01/75-xs650b-wiring-circuit-diagram-2.jpg
If you go from ignition lock .. To Right handlebar ( Handle switch right )
I Assume I is the normal drive Position
It is a red / yellow power in to the the light switch
And it goes out to one Blue as well as a Blue / Black
The Blue goes to taillight but also to the left to some minor things
The Black and Blue goes to the left handlebar switch first before it goes to the headlamp.
I believe it is rare that the wire itself is causing the problem
So perhaps in one of those switches.
Now we need to be careful so we dont get rid of the hard fault.
Feel free to draw own conclusions.
Perhaps with the resistance meter hooked up where the battery was
and if the fault is still there showing low resistance.
Then try to disconnect the blue at the right handlebar
( Assuming the Taillight )
If Resistance increases .. its there
No change back in with the blue and instead remove the other.
Again I apologize if this was to simple You might be an electrical Engineer.
And it can be solved by now
I had a problem with the left switch a month ago. Lot of insects inside Earwigs
And Dirt. No fuse burn though
Not sure where we are .
Perhaps it is fixed
Or sure of your competence with a wiring diagram
Some hints
If you still are in the position of "Hard Fault " as Jim calls it
There is a fair possibility to remove the battery
And have the fuse there.
The fuse burns because the + connects to - ( bare with me if this oversimplified )
So if you take out the battery and hook up your Voltmeter. There Clamp it with something or hold it .There should be resistance. Switches off.
Now you can turn lock push buttons and watch the resistance meter
Ignition On --and then the dodgy Light switch.
And so on
( Again bare with me if this oversimplified )
At the Schematic
https://thexscafedotcom.files.wordpress.com/2012/01/75-xs650b-wiring-circuit-diagram-2.jpg
If you go from ignition lock .. To Right handlebar ( Handle switch right )
I Assume I is the normal drive Position
It is a red / yellow power in to the the light switch
And it goes out to one Blue as well as a Blue / Black
The Blue goes to taillight but also to the left to some minor things
The Black and Blue goes to the left handlebar switch first before it goes to the headlamp.
I believe it is rare that the wire itself is causing the problem
So perhaps in one of those switches.
Now we need to be careful so we dont get rid of the hard fault.
Feel free to draw own conclusions.
Perhaps with the resistance meter hooked up where the battery was
and if the fault is still there showing low resistance.
Then try to disconnect the blue at the right handlebar
( Assuming the Taillight )
If Resistance increases .. its there
No change back in with the blue and instead remove the other.
Again I apologize if this was to simple You might be an electrical Engineer.
And it can be solved by now
I had a problem with the left switch a month ago. Lot of insects inside Earwigs
And Dirt. No fuse burn though
Just a comment to ponder: The blue tail light wire has caused problems in the pass. Its insulation can wear through in the region between the tank and tail light unit then short to ground and take the whole bike down on a single fuse system. Also, do not forget that 5twins mentions this same possibility of a short at the head light unit end due to insulation getting rubbed through.
Sorry if my comment is a bit out of place, but when I wrote it there were only 4 Pages to this thread. I see 5twins had already mentioned the Blue wire. This has happened to me before, must be a cache error.
Keep working well and I hope to see this all sorted soon.
Keep working well and I hope to see this all sorted soon.
Shipper
XS650 Addict
Sorry guys - missed today due to prior family commitments. Unavoidable. Back on it tomorrow morning. Will update tomorrow. Thanks to all of you.
Shipper
XS650 Addict
OK, I'm back...at least for a few hours. Got your instructions Jan_P and will test that out. The hard fault remains. Even when I just turn power on but donI't start the bike, the lights switch will blow the fuse. I am assuming (and no, I am not by any means a NASA engineer and your instructions I can follow but hardly over simplified for my pay grade), that the light circuit is in fact the problem. Finding the fault on the circuit is a whole nother issue.
Shipper
XS650 Addict
Okay, battery out, multimeter set to 2M, pointers on multimeter touch - '0' reading. Hook to battery leads - 1.0 reading. Power switch to position 1, flash '.55' and immediately back to '0'. light switches on in sequence - both '0' reading. Power 2 position - flash '.18' and immediately back to '0'. Light switches on in sequence - both '0' reading.
You've picked a hard row to hoe there young grasshopper.
Everything that's powered when you turn the key on has resistance. Since there's multiple items... and they're in parallel, it's gonna be a low value... smaller than the smallest and all that. For instance; each coil is 4Ω. Two 4Ω coils in parallel will have you down to 2Ω's. Throw in the tail light at about 2.5Ω and you're down to 1.1Ω. 4 instrument bulbs at 5Ω each will have you down to about a half an ohm.... of normal system resistance. What you're trying to do is in the proverbial needle in a haystack range of searches.
You can do it this way, but in order to do it, you'll have to unplug everything that draws current with the key on. Just off the top of my head, disconnect both coils, the regulator, the rectifier (it'll backfeed to the stator).... you'll need to remove the tail light bulb and all the little peanut bulbs in the tach and speedo.
It would be easier to just buy a handful of fuses.
Everything that's powered when you turn the key on has resistance. Since there's multiple items... and they're in parallel, it's gonna be a low value... smaller than the smallest and all that. For instance; each coil is 4Ω. Two 4Ω coils in parallel will have you down to 2Ω's. Throw in the tail light at about 2.5Ω and you're down to 1.1Ω. 4 instrument bulbs at 5Ω each will have you down to about a half an ohm.... of normal system resistance. What you're trying to do is in the proverbial needle in a haystack range of searches.
You can do it this way, but in order to do it, you'll have to unplug everything that draws current with the key on. Just off the top of my head, disconnect both coils, the regulator, the rectifier (it'll backfeed to the stator).... you'll need to remove the tail light bulb and all the little peanut bulbs in the tach and speedo.
It would be easier to just buy a handful of fuses.
Last edited:
You're looking for a dead short.... 0Ω. Set your meter to the lowest setting... should be the 200Ω scale.
Shipper
XS650 Addict
Or perhaps a brand new wiring harness. Think I’m done looking for that needle. Checked light switch components and all appears normal. Don’t feel like ripping a dilapidated wiring harness apart just to have it fail elsewhere.
Thanks for all your help guys. Will make the decision in next few days.
Shipper
XS650 Addict
Probably just 10amp fuse those coils just to say I covered the base but really not confident that’s where the problem is.
Shipper
XS650 Addict
Momma never raised no quiter! So consider the following. Unhooked the multimeter and replaced the battery (head lamp was in and out of bike for previous testing routine but left out at time of restart). Bike ran great, would not blow a fuse. Replaced headlamp, bike ran great, would not blow a fuse and thats with headlamp and high beams switched on). Switched ignition to 2nd setting (running lights) BIKE SHUTS DOWN BUT NO BLOWN FUSE. - WTF!!
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