Diagnostics/Troubleshooting; General; Voltage Drops - Buell 2008 XB SERIES Electrical Diagnostics Manual

DIAGNOSTICS/TROUBLESHOOTING

GENERAL

The troubleshooting tables in
GNOSIS contain procedures to solve and correct most common
problems. The

1.5 DIAGNOSTICS/TROUBLESHOOTING,

Voltage Drops

procedure below will help you to locate poor
connections or components with excessive voltage drops.
VOLTAGE DROPS
Check the integrity of all wiring, switches, fuses and connectors
between the source and destination.
The voltage drop test measures the difference in potential or
the actual voltage dropped between the source and destination.
1. See ITEM A in Figure
the most positive part of the circuit, which in this case
would be the positive post of the battery.
2. See ITEM B in Figure 1-5. Attach the black meter lead to
the final destination or component in the circuit (solenoid
terminal from relay).
3. Activate the starter and observe the meter reading. The
meter will read the voltage dropped or the difference in
potential between the source and destination. An ideal
circuit's voltage drop would be 0 volts or no voltage
dropped, meaning no difference in potential.
4. See ITEM C in Figure 1-5. An open circuit should read 12
volts, displaying all the voltage dropped, and the entire
difference in potential displayed on the meter.
Open circuits on the ground side will read zero.
1.3 STARTING SYSTEM DIA-
1-5. Attach your red meter lead to
NOTE
5. Typically, a good circuit will drop less than 1.0 volt. If the
voltage drop is greater, back track through the connections
until the source of the potential difference is found. The
benefits of doing it this way are speed and accuracy.
a. Readings aren't as sensitive to real battery voltage.
b. Readings show the actual voltage dropped, not just
the presence of voltage.
c. This tests the system as it is actually being used. It
is more accurate and will display hard to find poor
connections.
d. This approach can be used on lighting circuits, ignition
circuits, etc. Start from most positive and go to most
negative (the destination or component).
6. See ITEM D in Figure
can be checked as well.
a. Place the negative lead on the most negative part of
the circuit (or the negative battery post). Remember,
there is nothing more negative than the negative post
of the battery.
b. Place the positive lead to the ground you wish to
check.
c. Activate the circuit. This will allow you to read the
potential difference or voltage dropped on the neg-
ative or ground circuit. This technique is very effective
for identifying poor grounds due to powdered paint.
Even the slightest connection may cause an ohm-
meter to give a good reading. However, when suffi-
cient current is passed through, the resistance caused
by the powdered paint will cause a voltage drop or
potential difference in the ground circuit.
2008 Buell XB Diagnostics: Starting / Charging 1-15
1-5. The negative or ground circuit
1.5