1998 HONDA CIVIC electrical ignition

How the Circuit Works
Seat Belt Warning
With the ignition switch in ON (ll) or START (lll),
battery voltage is applied to the seat belt reminder
light. When the seat belt is not buckled, the seat
belt reminder/key-on beeper circuit in the
integrated control unit senses ground through the
closed seat belt switch. The seat belt reminder light
comes on and stays on, and the beeper beeps for
6 seconds. The reminder light and beeper will stop
when the seat belt is buckled or the timer circuit
deactivates them.
lgnition Key Warning
Battery voltage is supplied at all times to the seat
belt reminder/key-on beeper circuit in the
integrated control unit. When you turn on the
ignition key switch the integrated control unit
senses ground. lf you open the driver's door, the
door switch closes, causing the beeper to sound
until the door is closed.
Refer to the Service Manual (Section 23, Electrical)
for specitic tests or troubleshootrng procedures.
73-1

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
(
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

Headlights (cont'd)
- How the Circuit Works
Low Beams
With the headlight switch in HEAD and the dimmer
switch in LO, current tlows through the headlight
switch. fuse 21 . fuse 22. and the low beam
tilaments to ground, and the low beams come on.
High Beams
With the headlight switch in HEAD and the dimmer
switch in Hl, current flows through the headlight
switch, dimmer switch, fuses 4, 5, and the high
beam filaments to ground, and the high beams
come on.
Current also llows through the high beam indicator
light to ground. The high beam indicator comes on
to remind the driver that the high beams are on.
Flash-to-Pass
The flash feature works with the headlight switch in
OFF, PARK, or HEAD (low beams). When you move
the flash-to-pass switch to ON, current flows
through the switch, fuses 4 and 5, and the high
beam filaments to ground, and the high beams
flash. The high beam indicator also flashes during
the flash operation. The flash function has no effect
if the high beams are already on
Daytime Running Lights (Canada)
When you turn the ignition to ON (ll) with the
parking brake released, the daytime running lights
control unit supplies battery voltage at the
WHT/RED wire. This voltage is applied to the high
beam headlights through the daytime running lights
resistor. Each high beam headlight receives less
than battery voltage causing them to come on at
reduced brightness.
lf the parking brake is set, a ground signal is applied
to the daytime running lights control unit at the
RED/GRN wire. lf the parking brake is set when you
first turn the ignition switch to ON (ll), the high beam
headlights will remain off until you release the
parking brake. Once the high beam headlights are
on, setting the parking brake will not turn them ofi.
When low or high beam operation is requested,
battery voltage from the headlight switch is applied
to the daytime running light control unit via the RED
wire. The daytime running lights control unit then
turns off the headlights.
Refer to the Service Manual (Section 23, Electrical)
for specific tests or lroubleshootrng procedures.
110-14

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

Ir
Security Control Unit Input Test
The following tests are performed with the electrical conneclor disconnected from the security control unit.
\;
12345X67I910
1112131415rol171819202122
TerminalNo.WireColorTest ConditionTest: Desired ResultPossible Cause il result is not obtained
2LT GRN/REDEach door opened,one at a timeCheck for conlinuity to ground:
There should be continuity.
Faulty door switch
An open in the wirea
3BLU/BLKTrunUHatch openCheck for continuity to ground:
There should be continuity.
aFaulty trunldhatch latch switch
An open in the wirea
10WHTUnder all conditionsCheck tor voltage to ground:
There should be batteryvoltage.
. Blown No. 6 (3A) fuse in theunder-hood fuse/relay box(HX, LX, EX, DX-V Si)
. Blown No. 54 (40A) fuse in theunder-hood fuse/relay box (CX, DX)
. Blown (3A) fuse in security in-linefuse holder (CX, DX)
. An open in the wire
11YEL(BLK/YEL
cx, DX)lgnition switch ON (ll)Check for voltage to ground:
There should be batteryvoltage.
. Blown No 3 (10A) fuse in theunder-dash tuse/relay box(HX, LX, EX, DX.V, Si)
. Blown (3A) fuse in the security in-linefuse holder (CX, DX)
. An open in the wire
BLKUnder all conditionsCheck for continuity to ground:
There should be continuity.
aPoor ground (G401, G402)
An open in the wirea
t5BLU/RED
lgnition key insertedinto the ignition keyswitch
Check for voltage to ground:
There should be 1 V or less.aPoor ground (G401, G402)
Faulty ignition key switch
An open in the wire
Short in the wire
a
a
algnition key removedfrom the ignition keyswitch
Check for voltage to ground:
There should be 4 V or more.
18GRYUnder all conditionsConnect to ground:
Horn should sound.
. Blown No.52 (15A) luse in theunder-hood luse/relay box
. Faulty horn
. Faulty horn relay
. An open in the wire
133-15

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.