1997 HONDA CIVIC Temperature

- How the Circuit Works
Battery voltage is supplied through tuse 56 to the
A,/C compressor clutch r€lay contacts at all times.
With the ignition switch in ON (ll), vollage is applied
to the coil of the A,/C compressor clutch relay
through fuse 17. When you push the A,/C switch
ON, and the heater fan switch is in position | , 2, 3,
or 4, a "ground" input is provided to the engine
control module (ECM) or powertrain control module
(PCM) through the l'lC thermostat and the l'lC
pressure switch.
The A,/C compressor clutch relay is grounded by the
engine control module (ECM) or powertrain control
module (PCM). When energized, the A'lC
compressor clutch relay allows battery voltage to
turn on the A,/C comDressor clutch.
The A,/C ON indicator light comes on when the A,/C
system is requested.
A,/C Thermostat
The A'lC thermostat is located on the evaoorator
housing. The A,/C thermostat turns off the A,/C
compressor clutch if the temperature at the
evaporator goes below 3'C (37'F). This prevents
condensation from freezing on the evaporator fins
and blocking the air delivery into the passenger
compartment. The blower motor will keep running
when the sensor turns off the comDressor.
A,/C Pressure Switch
The fuC oressure switch is located in the condenser
outlet line where refrigerant is in a high
temperature/high pressure liquid state. The switch
will sense abnormally high or low pressure, and
open the circuit. This removes ground, and the
compressor will stop running.
Thermal Protectot
The thermal protector, located on the A,/C
compressor, opens and turns the compressor off if it
senses high temperature. Once the compressor
cools, the switch will close and the compressor will
begin running again.
Refer to the Service Manual (Section 22,
Air Conditioning) for specific tests or
troubleshooting procedures.
62-3

Fans
- AllModels\,1 |
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63

- How the Circuit Works
Radiator Fan
Voltage is provided at all times to the radiator fan
relay (contacts) through fuse 57. With the ignition
swilch in ON (ll), voltage is provided to the coil of
the relay through luse 17.
The radiator tan relay can be grounded through
either the engine coolant temperature switch or the
engine control module (ECM) or powertrain control
module (PCM).
The engine coolant temperature switch grounds
the radiator fan relay (coil) when the engine
coolant temperature exceeds 199'F (83'C). The
switch opens when coolanl temperature
decreases 3'- 8'C.
Condenser Fan
Voltage is provided at all times to the condenser fan
relay (contacts) through fuse 56. With the ignition
switch in ON (ll), voltage is provided to the coil of
the relay through fuse 17. When you push the A'lC
switch and put the heater fan switch in 1, 2,3, o( 4
position, the ly'C thermostat comes on, the
condenser fan relay energizes, and the condenser
fan motor runs.
A,/C Thermostat
The A,/C thermostat is located on the evaporator
housing. The A,/C thermostat tums off the A/C
compressor clutch if the temperature at the
evaporator goes below 3'C (37'F). This prevents
condensation from freezing on the evaporator fins
and blocking the air delivery into the passenger
compartment. lf the temperature goes below 3'C
(37"F) tuming off the Ay'C thermostat, ground will be
removed from the condenser fan relay. This will
deenergize the relay and remove voltage from the
condenser fan motor causing the fan to stop running.
Reter to the Service Manual (Section 23, Eleckical)
for specific tests or troubleshooting procedures.
63-3

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

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 Views (conrd)
71. Gauge Assembly
- Left side of dash
Connector A (A/T only)
- Green- On dashboard wire harness
1 YEL (lgnition input)
2 RED/BLK (Headlight
switch ON input)
3 RED(Dash light brightnesscontroller input)
4 BLU (L or 2indicator control)
6 D16Y7/D16Y8:BRN (Not used)
8 BLK (G401)
Connector B
- Blue- On dashboard wire harness
2 BLK (G401)
3 BLU/BLK (Trunk openindicator light control)
4 GRN/YEL (Hazard
warning switch input)
5 GRN/RED(Brake system indicatorlight control)
6 RED/BLU (Seat beltindicator light control)
7 '96-'97 model: BLU,ryEL(not used)
8 Except GX: GRN/YELGX: 8LU/GRN(Low fuel indicator lightcontrol)
9 D16Y7/D16Y8: YEL01685/016Y5:GRN/BLK(D4 or D indicatorcontrol)
10 GRN (03 or Sindicator control)
11 RED(N indicator control)
12 WHT(F indicator control)
13 BLI(BLU(P indicator control)
14 LT GBN(Park/neutral output)
10 Except GX: YEUBLKcX: ORN/BLU(Fuel gauge controlinput)
11 BLUAVHT(Vehicle speed sensor(VSS) input)
12 YEUGRN (Engine
coolant temperaturesending unit input)
14
15 BLI(IVHT(lgnition input)
16 WHT/BLU(Charging systemindicator light control)
202-30
Connector C
- Blue- On dashboard wire harness
1 *: YEL (lgnition input)
2 *: PNK (Washer lluidlevel input)
3 YEUBED(Low oil pressureindicator light control)
4 YEL (lgnition input)
5 GRN/ORN (Malfunctionindicator light control)
6 RED/GRN
{Lights on Hl input)
7 GBN/RED (Hazardwarning switch input)
*= '99-'00: All except CVT
Connector D
- Orange- On dashboard wire harness
BLU/RED (ABS
indicator light control)
8 BLU(Engine speed input)
10
12 FED(Dash light brightnesscontroller input)
13 RED/BLK (Headlightswitch ON input)
I
2
3
4
5
BLK (G401)
YEL (lgnition input)

Connector ldentification and Wire Harness Routing
Connector
or
Terminal
Number ot
Cavities/
Golor
LocationConnects toNotes
Engine Wire Harness (Dl6Y5, D16Y8 engines): '96-98 models and '99;00 D16Y5 dM/T
c101
c102
c 103
c104
Q104
c105
c106
c107
cl 08
cl09
cl10
c1l1
cl'12
c113
c114
c'115
c116
c'117
c 118
c119
c120
c121
c122
c123
c123
c124
Q124
c125
c 126
c127
c128
c129
c130
c131
cl32
c 134
c135
c136
c137
c138
c139
c'140
c141
c142
c143
c144
c'|44
c145
c146
c147
1O-GRY
3.GRY
1-CLR
4-GRN
3-N/A
2-BLK
2-BLK
2-BLK
2-BLK
3-GRY
3-GRY
3-GRY
2.BLK
2.GRY
2-BLK
14-BLU
14-GRY
3.GRY
2-BLK
2-GRY
1O-GRY
1.BLK
2.GRY
4-GRY
8-GRY
2-GRY
2.GRY
4-GRY
2.BLK
2.BLK
2-GRY
1.BLK
2O.BRN
22.GRN
32.GRY
25.GRY
31-BLU
16.GRY
14-GRY
8.GRY
2-GFIY
2.GRY
1-GRY
2-GRY
2-BLK
2-GRY
2.BLK
3-GRY
6-GRY
2.BLK
8-GRY
2-BLK
Left side of engine compartment
Left side of engine
Middle of engineI att .i.la ^f an^i^6
Left side ot engine
Middle of engine
Middle of engine
Middle of engine
Middle of engine
Middle of engine
[,liddle of engine
Middle ot engine
Middle ot engine
Middle of engine
Middle of engine
Middle of engine
l\,liddle of engine
Right side of engine compartment
Right side of engine compartment
Middle ot engine
Middle of engine
Middle of engine
Middle of engine
l\,liddle of engine
Nliddle of engine
Middle ot engine
Middle of engine
Middle ot engine
Middle of engine
Middle of engine
Nliddle of engine
Right side of engine
Under right side of dash
Behind right kick panel
Below right front footrest
Below right front footrest
Below right front footrest
Below right front tootrest
Left side ot engine compartment
Left side of engine compartment
Middle of engine
liliddle ot engine
Middle of engine
Nriddle ol engine
Right side of engine compartment
Middle ol engine
Right side of engine compartment
Middle of engine
N,liddle of engine
Right side of engine compartment
Right side of engine compartment
Bight side of engine compartment
Main wire harness
CKF sensor
Engine oil pressure switch
Alternator
Alternator
No. 1 fuel injector
No. 2 fuel injector
No. 3 fuel injector
No.4 fuel injector
IAC valve
TP sensor
MAP sensor
IAT sensor
Power steering pressure switch
EVAP purge control sol€noid valve
Junction connector
Junction connector
Vehicle speed sensor (VSS)
Countershatt speed sensor
Engine coolant temperature switch
Distributor
Engine coolant temp. sending unit
ECT sensor
Primary HO2S (sensor '1)
Primary HO2S (sensor '1)
Back-up light switch
Lock-up control solenoid valves
Secondary HO2S (sensor 2)
lvlainshafl speed sensor
Lanear solenoid
Shift control solenoid valves
Starter solenoid
Junction connector
Main wire harness
ECM/PCM connector A
PCM connector B
ECM/PCNI connector C
ECM/PCl\,,| connector D
Main wire harness
Maln wire harness
Knock sensor (KS)
IAC valve
VTEC solenoid valve
VTEC pressure switch
EVAP control canister vent shut valv€
EGR control solenoid valve
Secondary gear shatt speed sensor
EGR valve
EGR valve
Drive pulley speed sensor
CVT transmission solenoid
Driven pulley speed sensor
USA
Canada
AlT
USA
'2( tr\
'3
-1 (M/r)
t\4/T'2 (Anl'1
'2 (An)'2 (Nr)'2 (AtT)
'2 (Atr)
-1 (An)-2( fi|
M/T
.1 (Arr).1 (A,T)"1 (A/r)-1 (M/r).1 (CVT),1 (cw)'1 (CVT)
203-2