nection to ground is good so the problem is between
the lamp and the power source.
To isolate the problem, connect the jumper be-
tween the battery and the lamp (B,
Figure 13
). If it
comes on, the problem is between these two points.
Next, connect the jumper between the battery and
the fuse side of the switch. If the lamp comes on, the
switch is good. By moving the jumper from one
point to another, the problem can be isolated to a
particular place in the circuit.
Pay attention to the following when using a
jumper wire:
1. Make sure the jumper wire gauge (thickness) is
the same as that used in the circuit being tested.
Smaller gauge wire will rapidly overhead and could
melt.
2. Install insulated boots over alligator clips. This
prevents accidental grounding, sparks or possible
shock when working in cramped quarters.
3. Jumper wires are temporary test measures only.
Do not leave a jumper wire installed as a permanent
solution. This creates a severe fire hazard that could
easily lead to complete loss of the motorcycle.
4. When using a jumper wire, always install an
inline
fuse/fuse
holder
(available
at
most
automotive supply stores or electronic supply
stores) to the jumper wire.
5. Never use a jumper wire across any load (a com-
ponent that is connected and turned on). This would
result in a direct short and will blow the fuse(s).
BASIC ELECTRIC TEST PROCEDURES
Voltage Testing
Make all voltage tests with the electrical connec-
tors still connected unless otherwise specified. In-
sert the test leads into the backside of the connector
and make sure the test lead touches the electrical
wire or metal terminal within the connector hous-
ing. Touching the wire insulation will yield a false
reading.
Always check both sides of the connector as one
side may be loose or corroded thus preventing elec-
trical flow through the connector. This type of test
can be performed with a test light or a voltmeter. A
voltmeter gives the best results.
NOTE
When using a test light, either lead
can be attached to ground.
1. Attach the voltmeter negative test lead to a good
ground. Make sure the part used for ground is not
insulated with a rubber gasket or rubber grommet.
2. Attach the voltmeter positive test lead to the
point (electrical connector, etc.) to be checked (
Fig-
ure 10
).
3. Turn the ignition switch on. When using a test
light, the test light will come on if voltage is present.
When using a voltmeter, note the voltage reading.
The reading should be within 1 volt of battery volt-
age. If the voltage is significantly less than battery
voltage, there is a problem in the circuit.
Voltage Drop Test
Since resistance causes voltage to drop, a voltme-
ter can be used to determine resistance in an active
circuit. This is called a voltage drop test. A voltage
drop test measures the difference between the volt-
age at the beginning of the circuit and the available
voltage at the end of the circuit while the circuit is
operating. If the circuit has no resistance, there is no
voltage drop so the voltmeter indicates 0 volts. The
greater the resistance in a circuit, the greater the
voltage drop reading. A voltage drop of 1 or more
volts indicates that a circuit has excessive
resistance.
Remember a 0 reading on a voltage drop test is
good. Battery voltage, on the other hand, indicates
an open circuit. A voltage drop test is an excellent
way to check the condition of solenoids, relays, bat-
tery cables and other high-current electrical
components.
1. Connect the voltmeter positive test lead to the
end of the wire or device closest to the battery.
2. Connect the voltmeter negative test lead to the
ground side of the wire or device (
Figure 14
).
3. Turn the components on in the circuit.
50
CHAPTER TWO
13
