Honda Civic Service Manual page 1830

Five-Step Troubleshooting
L Verify The Complaint
Turn on all the components in the problem
circuil lo check the accuracy of the customer
complaint. Note the symptoms. Do not begin
disassembly or testing until you have
narrowed down the problem area.
2. Analyze The Schematic
Look up the schematic for the problem
circuit. Determine how the circuit is
supposed to work by tracing the current
paths lrom the power source through the
circuit components to ground. Also, trace
circuits that share wiring with the problem
circuit. The names of circuits that share the
same fuse, ground, or switch, and so on, are
referred to in each circuit schematic. Try to
operate any shared circuits you didn't check
in step 1 . lt the shared circuits work, the
shared wiring is OK, and the cause must be
in the wiring used only by the problem
circuit. lf several circuits fail at the same
time, the fuse or ground is a likely cause.
Based on the symptoms and your
understanding of the circuit's operation,
identify one or more possible causes.
3. lsolate The Problem By Testing The Circuit
Make circuit tests to check the diagnosis
you made in step 2. Keep in mind that a
logical, simple procedure is the key to
efficient troubleshooting.
Test for the most
likely cause of failure first. Try to make tests
at points that are easily accessible.
4. Fix The Problem
Once the specific problem is identified,
make the repair. Be sure to use proper tools
and safe procedures.
5. Make Sure The Circuit Works
Turn on all components in the repaired
circuit in all modes to make sure you've
fixed the entire problem. ll the problem was
a blown fuse, be sure to test all of the
circuits on that fuse. Make sure no new
problems turn up and the original problem
does not recur.
Test Equipment
Most circuits include solid-state devices.
Test the voltages in these circuits only with
a 1o-megaohm
or higher impedance digital
mUltimeter. Never use a test light or analog
meter on circuits that contain solid-state
devices. Damage to the devices may result.
Test Light and DVOM
On circuits without solid-state devices, use a
test light to check for voltage. A test light is
made up of a 12 volt bulb with a pair of leads
attached. After grounding one lead, touch the
other lead to various points along the circuit
where voltage should be present. The bulb
will go on if there is voltage at the point being
tested. lf you need to know how much
voltage is present, use a digital
volVohmmeter (DVOM).
Self-Powered Test Light and DVOM
Use a self-powered test light to check for
continuity. This tool is made up of a light bulb,
battery, and tlvo leads. To test it, touch the
leads together: the light should go on.
Use a self-powered test light only on an
unoowered circuit. First, disconnect the
battery, or remove the fuse that feeds the
circuit you are working on. Select two points
in the circuit belween which you want to
check continuity. Connecl one lead of the
self-powered test light to each point. lf there
is continuity, the test light's circuit will be
completed, and the light will go on.
SELF-POWERED TEST LIGHT
lf, in addition, you need lo know exacW hc'.
much resistance there is between two oo'^=
use a digital volUohmmeter (DVOM)
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