1997 HONDA CIVIC Electrical troubleshooting

How the Gircuit Works
All Except GX
Do not smoke while working on the fuel system.
Keep open flame away trom the work area. Drain
fuel only into an approved container.
A thermistor is mounted in the fuel tank unit. When
the thermistor is cool, its resistance is very high.
When the thermistor's temperature increases, its
resistance decreases. Fuel in the fuel tank transters
heat away lrom the thermistor fast enough to keep it
cool so the thermistor's resistance stays high and
lhe low fuel indicator light does not come on. When
the fuel level drops below the thermistor, the
thermistor's temoerature increases. Without the fuel
to cool it, the thermistor's resislance decreases,
allowing current to llow through the low fuel
indicator light and the thermistor to ground, and the
low fuel indicator light comes on.
Refer to the Service Manual (Section 23, Electrical)
for specific tests or troubleshooting procedures.
GX
The PCM turns on the low fuel indicator light when
the fuel level is low. The PCM will also blink the
indicator light when a problem is detected by the
fuel tank pressure sensor or the fuel tank
temperature sensor.
Refer to the Service Manual GX Supplement
(Section 11 , Fuel and Emissions) for specific tests
or troubleshooting procedures.
74-1

Gauges (cont'd)
- How the Gircuit Works
When the ignition switch is in ON (ll) or START (lll),
battery voltage is supplied through fuse 25 to the
gauges in the gauge assembly.
Speedometer and Odometer
The odometer and soeedometer drive circuits
receive pulses from the vehicle speed sensor
(VSS). The pulse rate increases as the car
accelerates. The frequency and duration of these
input pulses are measured and displayed by the
speedometer, odometer and tripmeter.
Tachometer
The tachometer drive circuit receives pulses from
the ignition control module (lCM) in the distributor
assembly or the ECM/PCM. The solid-state
lachometer then displays these pulses as engine
speed. For each 200 pulses per minute from the
ignition control modul€ (lCM) or the ECM/PCM, the
tachometer displays 100 RPM.
Engine Coolant Temperature Gauge
The engine coolant temperature gauge has two
intersecting coils wound around a permanent
magnet rotor. Voltage applied to the coils, through
fuse 25, generates a magnetic lield. The magnetic
field, controlled by the coolant temperature sending
unit, causes the rotor to rotate and the gauge
needle to move. As the resistance in the sending
unit varies, current through the gauge coils
changes. The gauge needle moves toward the coil
with the strongest magnetic field.
The 6ngine coolant temperature sending unit's
resistance varies from about 137 ohms at low
engine temperature to between 3H6 ohms at high
temperature (radiator fan running).
Refer to the Service Manual (Section 23, Electrical)
for specific tests or troubleshooting procedures.
81-2
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Fuel Gauge (All except cX)
The fuel gauge has two intersecting coils wound
around a permanent magnet rotor. Voltage applied
to the coils, through tuse 25, generates a magnetic
field. The magnetic field, controlled by the fuel
gauge sending unit, causes the rotor to rotate and
the gauge needle to move. As the resislance in the
sending unit varies, current through the gauge coils
changes. The gauge needle moves toward the coil
with the strongest magnetic field.
The fuel gauge sending unit's resistance varies
from about 2-5 ohms at full, to about 110 ohms at
empty. When you turn the ignition switch off, the
gauge remains at the last reading until you turn the
ignition switch to ON (ll) or START (lll) again,
Refer to the Service Manual (Section 23, Electrical)
for specific tests or troubleshooting procedures.
Fuel Gauge (GX)
The fuel gauge has two intersecting coils wound
around a permanent magnet rotor. Voltage applied
to the coils, through fuse 25, generates a magnetic
field. The magnetic field, controlled by the PCM,
causes the rotor to rotate and the gauge needle to
move. The PCM calculates the gas quantity in the
fuel tank by using the fuel pressure value detected
by the tuel tank pressure sensor and the fuel
temperature value detected by the fuel tank
temperalure sensor, and outputs the signal to the
gauge assembly. The gauge needle moves toward
the coil with the strongest magnetic field.
When you turn the ignition switch off , the gauge
remains at the last reading until you turn the ignition
switch to ON (ll) or START (lll) again. When the
PCM detects a malfunction with the fuel pressure or
temperature, or detects a gas leak, the PCM
reduces the fuel meter to 0.
Refer to the Service Manual GX Supplement
(Section 11 , Fuel and Emissions) for specific tests
or troubleshooting procedures.
a
a

Front WiperMasher (cont'd)
- How the Circuit Works
When the ignition switch is in ON (ll) or START (lll),
battery voltage is applied to lhe combination wiper
switch. and the windshield wiDer motor.
Low Speed
When you turn the wiper switch to LO, the wiper
motor's low speed winding is grounded through the
BLU wire and the LO speed contacts of the wip€r
switch at G401, and the wipers run at low speed.
ParUOfl
When you turn the wiper switch OFF, the integrated
control unit (PARK input) grounds the wiper motor
through the BLUMHT wire. The cam switch on the
motor signals the integrated control unit that the
wipers are in the PARK position; the control unit
then removes ground from the motor, and the
wipers stop in the PARK position.
High Speed
When the wiper switch is in Hl, the high speed
windings of the windshield wiper motor are
grounded through the BLUIrEL wire and the Hl
contacts of the wiper switch at G401, and the
wipers run at high speed.
Intermittent
When the wiper switch is in lNT, battery voltage is
applied through the YEUBLU wire to the integrated
control unit (lntermittent wiper ON input). The
integrated control unit (lnt€rmittenvPark Wiper
Control) grounds the low speed windings of the
wiper motor and the wipers make a single sweep
every few seconds (See Low Speed above). When
the wiper retums to the PARK position, the park
switch applies battery voltage through the
BLUMHT wire to the integrated control unit (PARK
input), and the wipers stop in the PARK position.
Mist
When you pull the wiper switch down to MIST
position, the high speed windings ot the wiper motor
are grounded through the BLU^/EL wire and the
closed contacts ot the mist switch at G401, and the
wipers make one pass across the windshield at high
speed. The ParUOff function then takes over and
the wipers stop in the PARK position.
Washel
When you pull the wiper switch toward you to turn
on the washer switch, battery vollage is applied to
the washer motor. The motor pumps fluid onto the
windshield until you release the lever; on '98r99
models, the integrated control unit (windshield
washer ON input) s€nses power at the WHT/BLK
wire terminal and runs the wipers whenever the
washer motor runs.
Refer lo the Service Manual (Seclion 23, Electrical)
for specific tests or troubleshooting procedures.
91-2

Power Windows (contd)
- How the Circuit Works
CAUTION: You could iniure your arms, hands, or
fingers if you unintentionally switch the driver's
window to "automatic down" while working in
that door with the power on. Disconnect the
window switch conneclot or the battery when
working in the driver's door.
System Description
The operation of the power windows is controlled by
the main switch in the power window master switch.
When the main switch is in OFF, only the driver's door
window can be opened or closed. With the main
switch ON, all windows can be ooened or closed
either by swtches in the master panel, or swttches in
the doors. The driver's window switch also has an
automatic down mode which is tumed on by pushing
the switch down to its second oosition.
The power windows are driven by reversible motors.
Each motor is protect€d by a built-in circuit breaker.
lf the window switch is held on too long (with the
window obstructed, or after the window is fully up or
down), the circuit breaker opens the circuit. The
circuit breaker resets automaticallv as it cools.
Driver's Window
With the ignition switch in ON, voltage is provided to
the coil of the power window relay through fus€ 24.
The contacts of the power window relay close, and
voltage is applied to the driver's switch. When you
push the power window master switch to UP, voltage
is applied to the driver's window motor. (The motor's
ground path is back through the master power
window switch.) The driver's window motor then
drives the window up. When you push the switch to
DOWN, voltage is applied in the opposite direction
and the motor drives the window down.
Automatic Down (Driver's Window)
With the ignition switch in ON or START, voltage is
applied to the coil of the power window relay. The
contacts of the power window relay close and
voltage is applied lo the power window master
switch. When you push the driveas switch to the
AUTO DOWN position, voltage is applied through
the driver's switch to the driver's window motor. The
control unit receives pulses at the pulser input while
the motor is running. When the window is fully
down, the motor stops, and pulses are no longer
generated by the pulser. This is sensed by the
control unit at the pulser input, and voltage is no
longer applied to the driver's window motor.
Passenger Windows
With the ignition switch in ON, voltage is applied to
the coil of the power window relay through fuse 24.
The contacts of the power window relay then close,
applying voltage to the individual window switches
and the power window master switch. With the
master panel main switch ON, the passenger
windows can be ooerated from the individual
window switches or from tho master panel switches.
When you push the front passengsr's window
switch to UP, voltage is applied to the f ront
passenger's window motor. (The motor is grounded
through the contacts in the front passenger's
window switch and the oower window master
switch.) The window moves up as long as you hold
the switch in the UP position. lf you push the switch
to DOWN, voltage is applied in th€ opposite
direction to the front passenger's window motor, and
the window movss down as long as you hold the
switch in the DOWN Dosition. The window switches
in the other doors operate similarly.
When you push the front passenger's switch in the
master panel to UP, voltage is applied through the
front passenger's window switch contacts to the
front passengefs window motor. (The motor is
grounded through the contacts in the front
passenger's window switch and the power window
master switch.) The window moves up as long as
you hold the switch in the UP position. lf you push
the switch to DOWN, voltage is applied in the
opposite direction to lhe front passenger's window
motor, and the window moves down as long as you
hold the switch in the DOWN position. The other
passenger window switches in the master panel
operate similarly.
Refer to the Service Manual (Section 23, Electrical)
for specific tests or troubleshooting procedures.
120-4

Moonroof (cont'd)
- How the Circuit Works
Moonroof Open
When you push the moonroof switch to the OPEN
position, the moonroof open switch applies ground
to the moonroof "open" relay through the YEL wire.
The moonroof "open" relay applies battery voltage
to the moonroof motor through the GRN/RED wire.
The moonroof "close" relay supplies ground to the
moonroof motor through its normally closed relay
conlacls. When the moonroof moves out of the fully
closed oosition. the tilvclose switch moves to the
OPEN position; the open/close switch moves to the
OPEN oosition.
Moonrool Tilt
When you push the moonroof switch to the TILT
position, the moonroot tilt switch applies ground to
the moonroof "close" relay through the BLU wire,
tilvclose switch and RED wire. The moonroof"close" relay applies battery voltage to the
GRNff EL wire to the moonroof motor. The
moonroof "open" relay supplies ground to the
moonroof motor through its normally closed relay
contacts. When the moonroof is in the tilt oosition,
the trlvclose switch moves to the TILTED position;
the open/close switch moves to the TILTED
Dosition.
Moonroof Close trom the Open Position
When you push the moonroof switch to the CLOSE
position, the moonroof "close" switch applies ground
to the moonroof "close" relay through the YEURED
wire, tilvclose switch and GRN/RED.wire. The
moonroof "close" relay applies battery voltage to the
GRNI/EL wire to the moonroof motor. The
moonroof "open" relay suppfies ground to the
moonroof motor through its normally closed relay
contacts. When the moonroof is fully closed, the
tilvclose switch moves to the closed position; the
open/close switch moves to the CLOSED position.
122-2
Moonroot Close from the Tilt Position
When you push the moonroof switch to the CLOSE
posilion, the moonroof "open" switch applies ground
to the moonroof "close" relay through the YEURED
wire, open/close switch and moonroof "open" relay.
The moonroof "open" relay applies battery voltage to
the moonroof motor through the GRN/RED wire. The
moonroof "close" relay supplies ground to the
moonroof motor through its normally closed relay
contacts. When the moonroof is fully closed, the
tilvclose switch moves to the closed oosition and the
open/close switch moves to the CLOSED position.
Refer to the Service Manual (Section 23, Electrical)
for specific tests or troubleshooting procedures.

How the Circuit Works
The two outside mirrors are controlled by the power
mirror switch. Each mirror has two reversible
motors: one motor moves the mirror up and down
and the other motor moves the mirror lett and right.
The power mirror switch contains four switches to
control mirror adjustment, and two switches to
select the left or right mirror With the ignition in ON
(ll), battery voltage is supplied to the power mirror
swrtch. The mirror selector switch directs voltage
from two of the direction switches to either the left
or the right mirror.
Mirror Up
When you press the "up" edge of the mirror
adjustment button, ground is supplied from one of
the up/down switch contacts to both mirrors; battery
voltage is supplied from the opposite up/down
switch contact through the mirror select switch. lf
the mirror select switch is in the left or right position,
battery voltage is supplied to the corresponding
mirror uo/down motor which then tilts the selected
mtrror uD.
Mirror Down
When you press the "down" edge of the mirror
adjustment button, battery voltage is supplied Irom
one of the up/down swilch contacts to both mirrors;
a ground is supplied from the opposite up/down
switch contact through the mirror select switch. lf
the mirror select switch is in the left or right position,
battery voltage is supplied to the corresponding
mirror up/down motor which then tilts the selected
mrrror oown.
Mirror Left
When you press the "|eft" edge of the mirror
adjustment button, battery voltage is supplied from
one of the lefuright switch contacts to both mirrors;
a ground is supplied from the opposite lefuright
switch contact through the mirror select switch. lf
the mirror select switch is in the left or right position,
battery voltage is supplied to the corresponding
mirror lefvright motor which then tilts the selected
mirror to the lett.
Mirror Right
When you press the "right" edge of the mirror
adjustment button, ground is supplied from one of
the lefvright switch contacts to both mirrors; battery
voltage is supplied from the opposite left/right switch
contact through the mirror select switch. lf the mirror
select switch is in the left or right position, battery
voltage is supplied to the corresponding mirror
lefuright motor which then tilts the selected mirror to
the right.
Refer to the Service Manual (Section 23, Electrical)
for speclfic tests of troubleshooting procedures
141-1

How the Circuit Works
The two outside mirrors are controlled by the power
mirror switch. Each mirror has two reversible
motors: one motor moves lhe mirror uo and down
and the other motor moves the mirror left and right.
The power mirror switch contains four switches to
control mirror adjustment, and a switch lo select
the left or right mirror. With the ignition ON (ll),
battery voltage is supplied to the power mirror
switch. The mirror selector switch directs voltage
Irom the direction switches to either the left or rioht
mtrror.
Mirror Up
When you press the "up" edge of the mirror
adjustment button, voltage is supplied from one of
the UP switch contacts to both mirrors. With the
mirror select switch in the LEFT or RIGHT Dosition.
ground is provjded for the corresponding up/down
motor through the opposite UP switch contact.
Battery voltage is supplied to the mirror up/down
motor which then tilts the selected mirror uo.
Mirror Down
When you press the "down" edge of the mirror
adjustment button, ground is provided through one
of the DOWN switch contacts to both mirrors.
With the mirror select switch in the LEFT or RIGHT
position, voltage is supplied to the corresponding
up/down motor through the opposite DOWN switch
contact. Battery voltage is supplied to the mirror
up/down motor which then tilts the selected
mtrror down.
Mirror Left
When the mirror select switch is in the LEFT or
RIGHT position, and you press the "lett" edge of the
mirror adjustment button, voltage is supplied to both
corresponding mirror motors through one of the
LEFT switch contacts. Ground is provided for the
corresponding lefvright motor through the opposite
LEFT switch contact, 8attery voltage is supplied to
the mirror left /right motor which then tilts the
selected mirror left.
I,J
141-3
Mirror Right
When the mirror select switch is in the LEFT or
RIGHT position, and you press the '?ight" edge of
the mirror adjustment button, ground is provided to
both corresponding mirror motors through one of
the RIGHT switch contacts. Voltage is supplied to
the corresponding leruright motor through the
opposite RIGHT switch contact. Battery voltage is
supplied to the mirror left /right motor which then
tilts the selected mirror right.
Mirror Detoggers
With the ignition switch in ON (ll), battery voltage is
supplied to the mirror defogger switch. When you
press the mirror defogger switch ON, voltage is
supplied to both mirror defoggers, causing them to
heat up and remove any fog from the mirrors. The
opposite side of each defogger grid is connected to
g rou no.
Refer to the Service Manual (Section 23,
Body Electrical) for specific tests and
troubleshooting procedures.