[TR] Electrical problem

[Ann and Tim Buja]

Randall wrote:
> One trick that might be helpful : a handheld magnetic compass should
> deflect when it comes close to a wire carrying DC current, as the wire
> generates a tiny magnetic field.  Also, if you let it sit with current
> flowing for awhile, you may be able to feel the warm wire.  (But not
> long enough to significantly overheat the fuse block and/or blow the
> fuse, of course.)

I like to use a sealed beam headlight for finding wiring faults.  Get some
good test leads with strong clips, connect the terminals of the sealed beam
(high or low beam) across the fuse clips and look for the fault.  The light
may illuminate dimly for actual load current through lights, fan motors,
etc.  When the light comes on at full brightness, you've found the area with
the fault, and when you've isolated the faulted section of the harness, the
light will dim or go out.  The bulb filament will limit any fault current to
(approximately) 60 watts / 12 volts = 5 amps so there's no risk of blowing
fuses or damaging your wiring or fuse block during the fault finding
process.

You can also clip the high and low beam terminals together to allow higher
fault current.  This could give you up to 9 or 10 amps of fault current in
case your compass is not sensitive enough.  The reduced resistance with both
filaments in parallel will allow more load current and may allow the
flashers to flash and fan or wiper motors to turn.

Tim Buja