There have been a number of questions on this and other sites about electrical wiring and repairs lately, so I thought I'd post an old Jag mechanic trick. If anybody else has a good shortcut or easy fix for something electrical, feel free to add it in.
If you have one of those frustrating wire breaks or a dead short someplace on the bike you can sometimes find it without disassembling and unwrapping the harness. All you need is or Boy (or Girl) Scout compass and a light duty turn signal flasher or a small circuit breaker. The local auto parts house should have a 10 or 15 amp one that will plug right in to your fuse block in place of a fuse.
Hold the compass about an inch or two away from the wiring on your bike. If the North pointer of the compass is pointing at the harness you'll have to reposition the bike a little. Ideally, you want the arrow pointing at about 90 degrees from the harness when the power is off. Now put the circuit breaker in place of your bad fuse and turn the ignition on. You should hear the breaker click on and off.
Slowly move the compass along the wiring harness. While the current is flowing, the needle will point to the bike, when you reach the short or break the needle will stop moving and point away. Now you know where to look for your problem.
This sure beats tearing the insulation off of half your harness to find the problem.
Good post Mike,
I'm not that great at "electrickery" so you have shown on old dog a new trick.
I see it's an old Jag trick. Having been a hard core "Teabagger" in the past I have had lots of experience with the frailties of Lucas, SU, Girling, etc. One thing about the Limeys though was they were pioneers in the "Exchange parts" business, or Recycling as we call it now.
Lonnie
And they were sane on wiring. Brown is always hot, black is always ground, white is ignition, yellow is charging, etc. I don't think any other country was as fanatic about that as the Brits.
There have been a number of times when I didn't need to pull up thirty year old carpet because of that little compass. I should have added that the cheaper air suspended compass works better than a liquid filled, but they both do work.
