Fuel tank HONDA CIVIC 1998 6.G Repair Manual

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(FUELTA}IKTEMPEB.ATURESENSOR
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FUEL TANKPRESSURESENSOnPHOTO 116
THROTTLEPOSrT|0NCIP)SENSOR
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25-6

Low Fuel Indicator Light
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74

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
(
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

103. Below Center of Rear Seat106. Inside of Left Rear Wheel (Right Similar)
104. Left Front Corner of Fuel Tank ('96-'98)107. Underside of Roof
105. lnside of Left Front Wheel (Right Similar)108. Left Underside of Hatch Lid
\
201-17

145. Left Side of Trunk (GX)
Gomponent Location
\148. Below Right Side of Center Console
146. Behind Back Seat (GX)
FUEL TANK PRESSURESENSOR AND FUEL TANKTEMPERATURE SENSOR(rNSrDE)
149. Underside of Vehicle, Left Rear of Engine (Si)
l47.Behind Left Side of Back Seat (GX)150. Right Front of Engine (Si)
201-24

Connector ldentification and Wire Harness Routing
Connector
or
Terminal
Number ot
Cavities/
Color
LocationConnects toNotesll-
Floor Wire Harness (Coupe/Hatchback)
c401
c401
c402
c503
v)az
ucco
ucc/
trcc/
u556
uccv
UCOU
c561
u30z
UCOZ
UCOJ
c564
u5b5
ucoo
uco/
trco.'
vcov
14.GRY
2O-GRY
4-ORN
16-BLU
16.GRN
8-GRN
25-GRY
2-NAT
25-GRY
2-NAT
1-WHT
2-GRY
1-WHT
2.ORN
14-GRY
2O-GRY
2-BRN
3.BRN
2.BRN
2-ORN
1-WHT
6-GRY
1O-GRY
Behind left kick panel
Behind left kick panel
Behind left kick panel
Below under-dash fuse/relay box
Behind under-dash fuse/relay box
Behind under-dash fuse/relay box
Driveas door
Driver's door
Passenger's door
Passenger's door
Below center console
Lett side of floor
Left B-pillar
Below left side of rear seat
Left quarter panel
Left quarter panel
Left quarter panel
Top of fuel tank
Top of fuel tank
Below right side of rear seat
Right B-pillar
Top ot fuel tank
Left side of dash
Main wire harness
Main wire harness
Main wire harness
Dashboard wire harness
Underdash fuse/relay box
Under-dash fuse/relay box
Driver's door wire harness
Drivefs door wire harness
Passenger's door wire harness
Passenger's door wire harness
Parking brake switch
Driver's seat belt switch
Driver's door switch
Left rear ABS wheel sensor
Rear wire harness
Rear wire harness
Rear wire harness
Fuel tank unit
Fuel pump
Right rear ABS wheel sensor
Passenger's door switch
Fuel tank pressure sensor
sub-harness
Power mirror switch
"1
'1
'2
"5
ABS
AEIJ'4
'5
'tI'D
-3
G552
Left kick panel
Left side of tloor
Body ground. via floor wire hamess
Body ground, via floor wire hamess
-1: With power windows "4: '96-98 models.2: Without oower windows .5: '99-'00 models.3: With fuel tank oressure sensor
203-28

Connector ldentification and Wire Harness Routing
Connector
ol
Terminal
Number of
Cavities/
Color
LocationConnects toNotes\
Floor Wire Harness (Sedan)
c401
c401
c402
c503
c551
trccz
vcco
ucc/
\,CC/
u55b
UCDY
UCOU
c561
lJcoz
ucoz
UCOZ
1'-coJ
lJ50.t
ucoc
ucoo
uco/
ucoo
c569
c570
c571
wJt z
TJC/J
v3/c
14-GRY
2O-GRY
4.ORN
16-GRN
16-GRN
8-GRN
25-GRY
2-NAT
25-GRY
2-NAT
1-WHT
2.GRY
1-WHT
2-ORN
8-GRY
16.GRY
20-GRY
2-BRN
3.BRN
2-BRN
2-OBN
1-WHT
6-GRY
1O-GRY
6-BLU
6.BLU'1-WHT
1.WHT
6-GRN
Behind left kick panel
Behind left kick panel
Behind left kick panel
Below under-dash fuse/relay box
Behind under-dash fuse/relay box
Behind under-dash fuse/relay box
Driver's door
Driver's door
Passenger's door
Passengels door
Below center console
Left side of floor
Right B-pillar
Below left side of rear seat
Left C-pillar
Left C-pillar
Left C-pillar
Left C-pillar
Top of fuel tank
Top ol fuel tank
Below right side of rear seat
Left B-pillar
Top of tuel tank
Left side of dash
Right B-pillar
Left B-pillar
Left quarter panel
Right quarter panel
Behind left side of rear seat
Main wire harness
Main wire harness
Main wire harness
Dashboard wire harness
Under-dash fuse/relay box
Under-dash fuse/relay box
Driver's door wire harness
Driver's door wire harness
Front passengeas door wireharness
Front passenger's door wireharness
Parking brake switch
Driver's seat belt switch
Front passenger's door switch
Left rear ABS wheel sensor
Rear wire harness
Rear wire harness
Rear wire harness
Bear wire harness
Fuel tank unit
Fuel pump
Right rear ABS wheel sensor
Driver's door switch
Fuel tank pressure sensor sub-harness
Power mirror switch
Right rear door wire harness
Lett rear door wire harness
Left rear door switch
Right rear door switch
Fuel sub-harness
-3, GX"4
ABS
"1
'1
ABS
GX
o
-3, GX
except GX
except GX
ABS
except GX
GX
G551
tftcz
Left kick panel
Left side of floor
Body ground, via floor wire hamess
Body ground, via floor wire hamess
.1 : With power windows -3: '96-'98 models except GX.2: Without power windows .4: '99-'00 models except GX
203-30

Connector ldentification and Wire Harness Routing
Connector
or
Terminal
Number ot
Cavities/
Color
LocationConnects toNotes
Rear Heated Oxygen Sensor Sub-harness
c782
4-GRY
4-GRY
Below front console
Below front console
Main wire harness
Secondary heated oxvoen sensor(Secondaiy HO2S) --
lrrr-
\y,.-
FUEL TANK PRESSURE SENSORSUB-TiARNESS
Fuel Tank Pressure Sensor Sensor Sub-harness
ucot'
c792
c793
6.GRY
3-BRN
2.BRN
Top of fuel tank
Left side of fuel tank
Left side of fuel tank
Floor wire harness
Fuel tank pressure sensor
EVAP two way valve
203-46
!'t

Connector ldentification and Wire Harness Routing
Connector
ot
Terminal
Numbor ot
CavitiesLocationConnects toNotest
t
Fuel Sub-Harness (GX)
uc/c
c682
c683
c684
6-GRN
2-GRY
3-N/A
2-GRY
Behind left side of rear seal
Left side of trunk
Middle ot trunk
Middle of trunk
Floor wire harness
Fuel lank internal solenoid valve
Fuel lank oressure sensor
Fuel tank temoerature sensor
FUEL SUB.HARNESS
203-48