Tracking down a short

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Jun 3, 2007 | 10:35 PM

Sharknose

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From: Midwest

Tracking down a short

After changing out the handlebars this weekend I'm now blowing 15 amp "Accessories" fuses on my Road Glide. It knocks out my turn signals and my speedo and tach both read zero.

I turned the ignition off, pulled the maxi fuse, put a new fuse in, then plugged the maxi fuse back in. When the maxi went in it sparked, (the ignition was still off). I pulled the replacement Accessories fuse and it was blown.

I probably pinched a wire in one of the clamps but I don't know where to start tracking down the one that's the problem. I've looked at the wiring diagram in the manual but all I get are crossed eyes. Any help on how to connect the voltmeter to track down the bad wire is appreciated.

Jun 4, 2007 | 10:21 AM

Sharknose

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From: Midwest

RE: Tracking down a short

After sleeping on this, I think I'm going to use a straight pin soldered to the ohmmeter's + lead to check each wire through the insulation, looking for one or more that are shorted to ground. Any reason why that wouldn't work?

Jun 4, 2007 | 12:36 PM

rh8234

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From: Lockport Township, IL

RE: Tracking down a short

First place I'd look is the switch housings. It is really easy to smash a wire between the bars and the housing, and that will cause the fuse to blow. Been there myself.

Jun 4, 2007 | 12:51 PM

Sharknose

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From: Midwest

RE: Tracking down a short

Agreed. I pulled both sides yesterday using the logic of "check the last change you made first". They look ok (no visible insulation chafing) and I wiggled them all around, but I didn't have a fresh fuse to try out to see if it fixed itself. I'd like to test it with a meter rather than using fuses for trial and error.

Jun 4, 2007 | 01:02 PM

peppi

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RE: Tracking down a short

Usually when a wire gets pinched enough to short out, you will see the impressions on it where it was pinched, it will be somewhat flat. It may save you a lot of time to just give it a good long look see.

Jun 4, 2007 | 03:17 PM

99igor

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RE: Tracking down a short

My methode of finding a short.

I make a test light using a 1157 or other suitable 12 v bulb. I solder two long wires to the bulb. One to the bottom of the bulb where it connects to a socket and the other to the side of the bulb (ground). On the other ends ofeach wire I solder a long large sewing needel. Make sure to buy new ones and do not use the ones your wife has!!!! I usually make the sires about 3 or 4 feet long.

Make sure the leads (wires are long enough so you can see the light from any where on the bike. WARNING-The light will get HOT!!!

Now, remove the blown fues. Push the needels into the poles of the fues. (Where the fues plugs in). The bulb will light brightly.

Now start wiggleing wires on the circuit where the short is. You are getting close when the bulb starts blinking or goes out. Continue wiggling until you find the short.

I have used this method for finding shorts in cars and bikes. It works! No meter, no expensive test lights, no other devices. The entire bulb setup costs no more that a few dollars.

Jun 4, 2007 | 06:27 PM

Sharknose

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From: Midwest

RE: Tracking down a short

If I understand, you're just replacing the fuse with the bulb. I assume that you have the ignition switch on since there is voltage present to light the bulb. Will the bulb just get hot, but not burn out?