Hi Beams

Just went to get my '82 XJ650 inspected - first ride of about 12 miles that she had since 1999 or so (PO had said it was running a few years ago - but inspection sticker was from 1999...)

Headlight seemed fine (I replaced the bulb) but when the inspector hit the high beams - nothing. Then - nothing on low OR high beams.

Seems the fuse self destructed. I'm sure I had played with this when ths bike was on the center stand idling in the shop and both high and low were fine. I replaced the fuse - same thing. (I'm a slow learner - so I went through a few fuses ).
Low beam was fine.. blown fuse on high beam. Could the vibration from the short ride have done something? Or maybe increased alternator output at 3-4000 rpm during the ride? Although - bike is just idling when this happens now.

I'm not even sure where to start troubleshooting... but she won't pass NY inspection without both high & low...

 

Stop replacing the fuses and replace the whole Fuse Panel.

 

Rick's right, replace the panel to a modern blade type panel. I ride with the stock panel, but it's been on my "to do" list since the main fuse blew during a ride from normal vibration. These bikes are notorious for fuse panel based problems. Also, the AGX 10 and 20 amp fuses are getting pretty scarce.
Even so, you shouldn't be regularly blowing the same fuse.
1)Do you have the correct rated fuse in the slot?
2)If so, are you overloading the circuit with a higher wattage bulb? (I believe the stock bulb is approx. 40/50w or 45/55w- Is you high beam wattage much over this?
3)It's also a good idea to do a physical inspection of the wiring, looking for any breaks which may cause a short.

 

headlight wouldnt work on our bike until i replaced the POS plastic fusebox.

now both beams work great

 

if the low beam is ok and high beam blows a fuse the problem must be unique to the yellow wire

 

Odd as it sounds, it might be the actual sealed beam headlight. With the bulb out I can flip the high/low beam switch and the fuse doesn't blow. and - the blue 'high beam' light comes on when it is supposed to. Again - no load since there is no bulb.

A multimeter seems to show 13+ volts at the socket in high or low beams
Oddly, when I test for continuity, I get voltage no matter what 2 of the 3 headlight prongs I test. Seems one pair should give me nothing..

At the socket, I need to pick the right pair of connectors to get voltage.

I guess I might just get a new bulb...

 

Nope.

If you look at Polock's diagram in the headlight one of your 3 is the ground. The High and Low connect to it via the filaments.

You won't find much change in resistance either. The filaments have very little until they get hot - which requires more amperage than your meter can provide.

 

po told me not to rock the high beam switch to the center,,, both low an high beams will light at the same time blowing the fuse,,,,,,sounds like a simular problem maybe the switch is not cutting the low off when you go to high beam or the bulb is shorting out to the low beam,,,,Dan

 

I'll take that switch apart and clean it. I guess that without a bulb, the fuse wouldn't blow under the above scenario...
Thats what was confusing me. I figured that if there was a short somewhere it would blow the fuse, even without a bulb!

Is there a way to test the relay?

 

just checking
this is a 10 amp fuse ?
the headlight relay is common to both high and low

 

don't know what hapened to my answer on last post but here it is again 3rd try

find the ground on the socket an check the other 2 for continuity there should be no continuity between high an low positive wires this should be true for the bulb as well

 

I love the high beams...

 

False: On a good bulb there is indeed continuity between the high and low beam positives. Both filaments share a common ground (earth for those with snow now ) so they have continuity.

 

yes - 10 amp fuse.. although I've had a 20 in there by mistake and it also blew. Can't see any obvious cuts in wires..

so - other than 'it works or it doesn't' there isn't a way to check for a bad bulb?
also - assuming that if the relay is common to high and low, and the low works, the relay is ok...

 

my apologies for the no continuity on the low an high bulb thing, great bunch of people here,,,,,and as far as I know I could be wrong on the low an high together blowing the fuse also,,,if this is wrong feel free I actually hope it is ,,,,,,If I get into this also I want to upgrade the bulb as far as posible.

sure does look like a bad bulb or to much watage,,,,,I'd have trouble replacing the fuse box 1st thing also,,,,,but if you think I'm butting heads with Rick,,,, now that's funny.

I'll tag along for obvious reasons

 

you could check the bulb with a battery charger, one lead on common the other to hi or low, then try common to the other two at the same time
a meter should show slightly lower on common to hi than common to low
common /hi and common/low should add up to hi to low
try a layer of tape under the switch or the switch not on the bars
check out the headlight plug closely maybe something happens when the prongs go in
try with the key on, switch on hi, plug in the light, if its ok the moving switch is suspect

 

Before this goes any further (sorry on my late jump-in), do you know how to 'read' a blown fuse? You say the fuse keeps 'blowing'... But the WAY it blows will tell you where to look for your problem.


(Sorry, I cant find the comparison pic I was looking for, so bear with me)

If the fuse element simply melts in half (you will probably see the element still attached to the ends of the fuse, with a gap in the middle and little balls of material melted at the gap), then it failed due to a current overload. This would happen from using an aftermarket headlight bulb that is rated higher than stock. (BTW, if it IS stock, then the wattages are 60/50, for a total of 110 watts. 110W@14V= just under 8 amps, which should not overload a 10A fuse under normal circumstances if the switch got 'stuck' in the middle). However, if you have a stock bulb and the fuse still blows from overload, then start looking at your connectors. Corroded connectors can add resistance to the circuit, thus increasing the current and blowing the fuse.

Now if the fuse element "explodes", leaving a soot mark and spatters of the element all over the inside of the glass tube, then it failed as the result of a short circuit. If this is the case, then start examining your wiring harness for loose/broken connectors, anything the PO might have added (could be wired wrong), chafed/split insulation on the wires, metal things that could have sliced/poked through a wire, etc. Any damage at all can cause a short.

Hope this helps

 

Great info for future reference, Taz. Thanks.

 

Nice tid-bit there Taz, never reasoned a frying fuse out like that.