Main fuse blowing immediately upon instillation?

R

Red45

XS650 Member
Messages
6
Reaction score
6
Points
3
Location
Canada
hello everyone, I was hoping someone might have experienced this problem before and have some ideas.
Bike is a 1980 650 xs special.
So here are the basics. Older battery wasn't holding a good charge but bike started and ran no problems. I decided to replaced the battery. Got a new one put a charge on it and placed in in the bike. As soon as it was connected the main 20 amp fuse went. I figured it was a bad fuse and got a replacement, as soon as I place the new fuse in and it makes contact with the connectors in the fuse panel it blows. Key doesn't even have to be in the bike just blows the main 20 amp immediately upon installation.
Any help or ideas would be greatly appreciated.
Thanks
 
Remove the other fuses, see if the main will hold, then reinstall fuses one at a time to help isolate the problem area.
 
One idea if the fuse is blowing with key off would be to attach a 12 volt light bulb across the terminals of the fuse holder. The light bulb will act like a non-blowing fuse if that make sense. Then with bulb lite up try wiggling things to see if moving harness and such causes the bulb to go out.

It will light up showing you there is a draw but will not draw enough to cause wires to melt.

Don't even think about putting in a heavier fuse because you don't want to find the short by tracing the smoke!
 
Red45 said:
hello everyone, I was hoping someone might have experienced this problem before and have some ideas.
Bike is a 1980 650 xs special.
So here are the basics. Older battery wasn't holding a good charge but bike started and ran no problems. I decided to replaced the battery. Got a new one put a charge on it and placed in in the bike. As soon as it was connected the main 20 amp fuse went. I figured it was a bad fuse and got a replacement, as soon as I place the new fuse in and it makes contact with the connectors in the fuse panel it blows. Key doesn't even have to be in the bike just blows the main 20 amp immediately upon installation.
Any help or ideas would be greatly appreciated.
Thanks
Click to expand...

You got a hard short Daddy-0. First I’d look at the + lead from the battery down the starter switch for a break in the casing.
 
Thanks guys, battery's is in correctly the leads arnt long enough to install it backwards. I like the light bulb idea I might try that. But first thinks first I'm going to try removing all other fuses and see if the main holds if it does then replace each fuse one at a time till the main does blow. It that works at all it will help me isolate it. Other than that I am going to take the advice of first following the positive lead to the starter looking for any cracks or wear. Thanks for the info/ideas guys and I will keep you up to date on the progress.
 
Red45 said:
Thanks guys, battery's is in correctly the leads arnt long enough to install it backwards. I like the light bulb idea I might try that. But first thinks first I'm going to try removing all other fuses and see if the main holds if it does then replace each fuse one at a time till the main does blow. It that works at all it will help me isolate it. Other than that I am going to take the advice of first following the positive lead to the starter looking for any cracks or wear. Thanks for the info/ideas guys and I will keep you up to date on the progress.
Click to expand...

Because it used to work....Take hard look at everything you touched. Good luck.
 
gggGary said:
yup left AND right hand batteries commonly found at the store in that size.
Click to expand...
And if nothing else seems to make sense you might need to be sure the polarity is right. Only saw it happen one time but it is possible to make a mistake hooking up a charger to a dead battery and charge it up in reverse. Positive become negative and vise a versa.

This was on a heavy equipment system but a lead acid battery is a lead acid battery. Like I said only once in about 45 years working on heavy equipment but once is all it takes. Lucky for us this was on an old-school machine no fancy electronics to fry. Just fully discharged battery and charge the right way and it was good as new once the generator was properly polarized.
 
650Skull said:
battery terminals wrong way round???
Click to expand...

When buying a battery for my XS, the battery offered to me had the terminals around the opposite way to what they needed to be on my bike.......Took me a few minutes thinking there is something nagging me when looking at the battery..........yep it was the terminals......
 
The Battery negative cable goes directly to the frame. On my 83 you can see it straight away. Odds are, you got the right battery and it is installed correctly. But have another look at it anyway.
There is always power at the main fuse whether the switch is on or off. If you don’t have a vom or Dvm, this might be a good time to get one. Pull all the fuses. Using the dc volts scale, Check for battery voltage on both sides of the main fuse holder. Connect the vom negative lead to the frame or any engine fin using an alligator clip. With the main fuse pulled on my bike there is 13 volts on the left side of the fuse slot, 0 volts on the right side. Using the ohmmeter check for resistance on the right or 0 volts side. There should be fairly high resistance to ground. It will be several mega ohms or OL if it is a dvm. If it is really shorting like you describe you will see much less resistance, possibly less than 100 ohms or near zero ohms. When you are done checking resistance, switch the meter off or back to dc volts scale. You don’t want to risk damaging the meter. Looking at the diagram, there doesn’t appear to be much hanging off of the main fuse that doesn’t go through the main switch. The only thing I can see is the regulator. If You suspect a short after the main fuse, you could try disconnecting the regulator to see if the short disappears. But odds are the short may be in the the cable harness.
Let me know what you find.
 
Bushyeyed was right to question my intelligence and I was wrong in not questioning the clerks intelligence... Lol It was reverse terminals.... They gave me a pretty much identical battery with reverse terminal despite me bringing in the old one and requesting a replacment of the same brand and telling them the make and model of the bike. I didn't even think to double check the terminals just the Amps and such. Well, lesson learned and at least I only went through two fuses before figuring it out. Thanks for the ideas and help guys, especially bushyeyed and 650skull.
 
Red45,

Thanks to you for reporting a solution to this one, way too often the solution does not get reported.

Glade despite the frustration of the screw-up it was a simple fix!
 
Red45 said:
Bushyeyed was right to question my intelligence and I was wrong in not questioning the clerks intelligence... Lol It was reverse terminals.... They gave me a pretty much identical battery with reverse terminal despite me bringing in the old one and requesting a replacment of the same brand and telling them the make and model of the bike. I didn't even think to double check the terminals just the Amps and such. Well, lesson learned and at least I only went through two fuses before figuring it out. Thanks for the ideas and help guys, especially bushyeyed and 650skull.
Click to expand...

Hi Red and welcome,
did the battery shop's boy genius swap you the correct battery cost free?
And Canada's a big country, which part are you situated in, eh?
 
Red45 said:
Bushyeyed was right to question my intelligence and I was wrong in not questioning the clerks intelligence... Lol It was reverse terminals.... They gave me a pretty much identical battery with reverse terminal despite me bringing in the old one and requesting a replacment of the same brand and telling them the make and model of the bike. I didn't even think to double check the terminals just the Amps and such. Well, lesson learned and at least I only went through two fuses before figuring it out. Thanks for the ideas and help guys, especially bushyeyed and 650skull.
Click to expand...
Glad the problem is resolved. This one is not your fault so don’t doubt your own intelligence.
You may still want to do some basic tests on the charging system though, just to make sure nothing got stressed in the regulator/rectifier. With the battery hooked up positive to ground, I think the short you were experiencing would have been through the rect/reg. These solid state units are robust, but after 49 years...who knows. Under certain degraded conditions the regulator can cause battery overcharging which would make short work of your new battery. There are some basic test procedures in the Haynes manual. Probably also find it on the forum.
 
fredintoon said:
Hi Red and welcome,
did the battery shop's boy genius swap you the correct battery cost free?
And Canada's a big country, which part are you situated in, eh?
Click to expand...
Yep they knew it was their mistake and swapped it no charge. I'm in Alberta just outside of Calgary in the Rockies.
 

Similar threads

bosco659
Blowing fuse?
2
Replies
29
Views
1K
bosco659
bosco659
G
Wiring Gremlin
Replies
12
Views
319
geeskeet
G
P
wiring question
Replies
3
Views
374
5twins
5twins
magoo66
Installed Rewound Alternator Rotor, now blowing fuses.
2
Replies
25
Views
1K
magoo66
magoo66
P
1976 XS650 keeps blowing main fuse
2
Replies
21
Views
2K
MaxPete
MaxPete
Back
Top