Short in Headlight circuit

[Stealth Biker]

I searched the tech pages and searched in vain for the short before making this post.  My headlight fuse blew last weekend so I replaced the fuse.  Worked fine for a day and then blew again.  Pulled the headlight assembly, checked all the visible wiring, and changed the headlight lamp.  On initial startup it works fine.  About a mile into the ride to work, the fuse blows again.  This weekend I needed to service my air filter so I pulled the tank, R and L Swich housings on the hadlebars and headlight assembly to find the short.  Nothing is visibly shorted.

When ohming out the fuse block, I get 2.6 ohms to ground on one side (R) of the headlight fuse block (with headlight removed).  When I pull the black 9 pin connector apart in headlight housing, I don't get a reading to ground.  Even stranger, when I pull the rear tailight housing fuse, I get a 2.6 ohm reading to ground on one side of this fuse connector but then the headlight fuse does not show any continuity to ground.  Maybe 2.6 ohms to ground is normal but if so then why isn't the short showing up on the meter?

If anyone has had a similar issue then any assistance would be appreciated.

To add injury to insult, while working on the electrical issues, I noticed a steady stream of fluid out of my L front fork.  Great!!!

[R J]

Have you added any thing to the bike recently, or done any maintenance?

If so, start there.

If not, check all your connections in the headlamp housing, and also under the right side cover,,

Don't just look at them, try them to make sure they are solid.

[Stealth Biker]

Haven't added anything in a couple of years.  I added the relay to isolate the headlight circuit from the start switch a couple years ago as well.  I have extra lights on the bike but they are on separate fuses and switches.  Haven't had any electrical problems up until now.

I have all the wires exposed under the right side cover and the headlight assembly.  Nothing is visibly shorted.

I was hoping someone else had experienced something like this.  Oh well with blown fork seals I won't be riding for a while anyway.

Thanks

[Madmike]

Remove all bulbs and check through the wiring to see if it goes to ground.  Power side (from source to bulb plug) should show infinite resistance to ground while the green wires are the ground side of the circuit and should show low resistance.  If you check the power side with the bulb in place you will (should) see a reading for the complete circuit through the bulb filament back to ground.

If your meter has a "tweet" selection you can hook it up with alligator clips and then move the harness around by probing with your hand and turn the handlebars from stop to stop to see if you can locate the short and listen for the meter to chirp if a circuit to ground is made.  Alternatively you can make up a tester using an electronic beeper, supply power to an open circuit through the beeper and then move the harness around and try and find a short to ground.

[rww930]

I experienced a very similar thing about a month ago. The cruise control (the manual kind with the thumb switch) was too close to the wires there and it kept shorting out. Took awhile but found the wires there slightly rubbed bare and shorting an inline fuse that protected my running lights. Good luck.

[Tinman]

If it were me I think I would try these 2 things first.
Check the ground for the headlight.
Try replacing the relay.
It may be  going bad.
Just one more thing is you have not replaced or upgraded the bulb itself to a
higher wattage have you. Also if the bulb is a few years old it could be it.

[Robert]

You are not going to be able to check for a short with a ohm meter because the short is intermittent unless you can make the short happen. But by that time you will have already located the problem. If you go up say 5 amps on the fuse for a short while and see if it blows this will tell you if its a good solid short or just a overage on voltage and it should not damage the wiring. The safe way to do this would be with a amp meter hooked in line or in place of the fuse and see what you get and if its excess draw or a short. If you sill get a short then you will have to start looking for the cause. The reading is more than likely from going through the filaments of the turn/running lights.