service HONDA INTEGRA 1998 4.G Workshop Manual

Air Deliver| (cont'd)
- How the Circuit Works
The air delivery system directs the flow of air used
by the heater and air conditioner systems.
Mode Selection
Mode selection is controlled by the mode switches in
the heater control panel and the mode control motor.
When you select a specific mode, voltage is applied
through the dimming control circuit to the LED, which
comes on, indicating the mode selected. Ground is
provided to the mode control motor though that
mode switch. The motor then runs until the air
control door reaches the proper position.
Fresh/Recirculation Selection
When you press the recirculation button, a ground
signal is sent from the heater control panel to the
recirculation control motor. The motor lhen runs
until the recirculation door reaches the opposite
Dosition. When the recirculation button is in the
REC position, battery voltage is applied through the
dimming control circuit to the recirculate LED, and
the LED comes on.
Refer to the Service Manual (Section 21, Heate0 for
specif ic tests or troubleshooting procedures.
61-2

A/C Gompressor Controls (conrd)
- How the Circuit Works
Battery voltage is supplied through fuse 56 to the
A,/C compressor clutch relay contacts at all times.
With the ignition switch in ON (ll), voltage 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 posation 1, 2, 3,
or 4, a "ground" input is provided to the engine or
powertrain control module (ECM or PCM) through
the A,/C thermostat and the A,/C pressure switch.
The A,/C compressor clutch relay is grounded by the
engine or powertrain control module (ECM or PCM).
When energized, the A,/C 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,/C thermostat is located on the evaoorator
housing. The AJC 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 lurns off the compressor.
A,/C Pressure Switch
The A,/C pressure 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.
Refer to the Service Manual (Section 22,
Air Conditioning) for specific tests or
troubleshooting procedures.
62-2

Fans (cont'd)
- How the Gircuit Works
When the ignition switch is in ON (ll), voltage is
applied to the coils of the radiator fan relay and the
condenser fan relay (with A,/C) through fuse 17.
Whenever a ground is provided to the radiator fan
relay and condenser fan relay, the relays are
energized, turning on the radiator fan motor and
condenser fan motor. The relays can be grounded
by the radiator fan switch, engine or powertrain
control module (ECM or PCM) (USA), or the A,/C
and heater lan switches via the A'lC pressure switch
and the A,/C lhermostat.
A,/C Thermostat
The A,/C thermostat is located on the evaporator
housing. The A/C thermostat turns oft the A/C
compressor clutch it the temperature at the
evaporator goes below 3'C (37"F). This prevents
condensalion from freezing on the evaporator fins
and blocking the air delivery into the passenger
compartment. lt the temperature goes below 3'C
(37'F) turning off the A"/C thermostat, and the
BLU/RED wire at the A,/C diode was the only wire
providing ground to the condenser and radiator
fan relays (A,/C switch on, heater fans switch on,
radiator fan switch open, and ECM or PCM fan
controi output not grounded), the relay will
deenergize removing voltage from the condenser
and radiator fan motors causing them to stop
running.
A,/C Pressure Switch
The AJC oressure switch is located in the condenser
outlet line where refrigerant is in a high
temperature/high pressure liquid state. The A,/C
switch turns off the A,/C compressor clutch if it
senses abnormally high or low pressure. lf the A'lC
pressure switch opens, and the BLU/RED wire at
the A/C diode was the only wire providing ground
to the condenser and radiator fan relays (L/C switch
on, heater fans switch on, radiator lan switch open'
and ECM or PCM fan control output not grounded),
the relay will deenergize removing voltage from the
condenser and radiator fan motors causing them to
stop running.
A./C Diode
This diode orevents the radiator fan switch f rom
grounding the "A'lC ON" input to the engine or
powertrain control module (ECM or PCM).
Refer to the Service Manual (Section 23, Electrical)
for specific tests or troubleshooting procedures.
63-3

- How the Circuit Works
Voltage is applied at all times through f use 50 to
the rear window defogger relay. With the ignition
swrtch in ON (ll), voltage is applied through luse
16 to the rear window defogger relay and the
defogger ON indicator.
When you turn the rear window defogger switch to
ON, a path to ground is provided for the rear
window defogger relay and the defogger ON
indicator through the integrated control unit. The
defogger ON indicator light comes on and the rear
window detogger relay contacts close. Voltage is
applied to the detogger grid on the surface of the
rear window and the grid heats the rear window to
remove any fog lrom the glass.
A timer in the integrated control unit will automatically
tum off the defogger atter 20 to 30 minutes.
Refer to the Service Manual (Section 23, Electrical)
for specific tests or troubleshooting procedures.
64-1

- How the Circuit Works
The low engine oil pressure indicator light works in
two ways: il flashes continuously following a
momentary loss of engine oil pressure, or it comes
on and stays on with a complete loss of engine oil
oressure,
When the engine first starts, before its oil pressure
rises above 4.3 psi, voltage is applied to the closed
and grounded engine oil pressure switch and the
light comes on to test the bulb.
With the engine running, voltage is applied at the
WHT/BLU wire of the integrated control unit. With
normal engine oil pressure, the engine oil pressure
switch is open and the low oil pressure indicator
light does not come on. lf the engine oil pressure
switch closes momentarily (more than 0.5 seconds)
but then opens again, the YEURED wire at the
integrated control unit will sense ground through the
switch. The integrated control unit will then provide
and remove ground for the low oil pressure indicator
light through the YEURED wire. The light will flash
on and off until you turn the ignition switch off. The
flashing feature will not work until 30 seconds after
initial voltage is applied to the WHT/BLU wire of the
oil pressure indrcator llasher circuit. This delay
keeps the low oil pressure indicator light from
coming on during engine warm-up.
lf engine oil pressure falls below 4.3 psi and does
not increase, the engine oil pressure switch will stay
closed. The low oil pressure indicator light will then
come on and stay on.
Refer to the Service Manual (Section 23, Electrical)
for specific tests or troubleshooting procedures.
72-1

- How the Circuit Works
Do not smoke while working on the fuel system.
Keep open flame away from 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 is warm, its resistance
decreases. Fuel in the fuel tank transfers heat away
from the thermislor last enough to keep it cool so
the thermistor's resistance stays high and the low
fuel indicator lighl does not come on. When the fuel
level drops below about 2.2 gallons, the thermistor
is no longer immersed in fuel. Without the fuel to
cool it, the thermistor's resistance decreases,
allowing current to flow through the low fuel
indicator light and the thermistor to ground, and lhe
low fuel indicator light comes on.
Refer to the Service Manual (Section 23, Electrical)
for specific tests or troubleshooting procedures.
74-1

Gauges (cont'd)
- How the Circuit 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 speedometer drive circuits
receive pulses lrom 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 ('98-'99 Models)
The tachometer drive circuit receives oulses from
the ignition control module (lCM) in the distributor
assembly. The solid-state tachometer then displays
these pulses as engine speed. For each 200 pulses
per minute from the ignition control module (lCM),
the tachometer displays 100 RPM.
Tachometer ('00 Model)
The tachometer drive circuit receives pulses f rom
the PCM or ECM. The solid-state tachometer then
displays these pulses as engine speed. For each
200 oulses oer minute trom the PCM or ECM the
tachometer displays 1 00 RPM.
Engine Coolant Temperature Gauge and Fuel
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 field. The magnetic
field, controlled by the engine coolant temperature
gauge 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 tield. The fuel gauge
works the same way.
The engine coolant temperature gauge sending
unit's resistance varies from about 137 ohms at low
engine temperature to between 30-46 ohms at high
temperature (radiator fan running).
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 to LOCK (0), the
gauge remains at the last reading until you turn lhe
ignition switch to ON (ll) or START (lll) again.
Refer to the Service Manual (Section 23, Electrical)
for specific tests or troubleshooting procedures.
81'2

How the Circuit Works
The maintenance reminder light comes on to
remind the driver that the car is due for
scheduled mainlenance.
The maintenance reminder unit receives a vehicle
speed input from the vehicle speed sensor (VSS)
and uses this inlormation to compute the distance
traveled. For the first 6000 t 1 00 miles (9650 t 160
km) after the maintenance reminder light is reset, it
will come on for two seconds when you turn the
ignition switch to ON (ll) as a bulb check.
Between 6000 1 100 miles (9650 t 160 km) and
7500 t 100 miles (12070 I 160 km) the reminder
light will come on for two seconds when you turn
the ignition switch to ON (ll), and then flash for eight
seconds more.
Beyond 7500 t 100 miles (12070 t l60 km) the
reminder light will stay on when the ignition switch is
in the ON (ll) position until the unit is reset.
To reset the unit, the car must be parked and the
ignition switch in the ON (ll) position. Press the
reset button on the unit and hold it there for more
than three seconds, and the reminder light will
go off.
Refer to the Service Manual (Section 23, Electrical)
for specific tests or troubleshooting procedures.
83-1

- How the Circuit Works
With the ignition switch in ON (ll) or START (lll),
voltage is applied to the A,/T gear position indicator.
The A,/T gear position switch provides a ground for
each position. As an input is grounded, ils indicator
light comes on. lf you se,ecl B, tor example, ground
will be applied to the input of the A,/T gear position
indicator, and the R indicator bulb will come on.
With the headlight switch in PARK or HEAD, voltage
is applied to the RED/BLK wire terminal. this
changes the indicator panel illumination from lixed
to controlled by the dash lights dimmer inpul
through the RED wire.
When the lransmission ('98.99 models) or
powertrain ('00 model) control module (TCM or
PCM) detects an abnormality in the automatic
transmission control system, or when you request
diagnostic trouble codes through the service
check connector, the TCM or PCM will make lhe D4
indicator light blink.
Refer to the Service Manual (Section 14,
Automatic Transmission) for soecific tests or
troubleshooting procedures.
89-1

Wiperffasher (contd)
- How the Circuit Works
When the ignition switch is in ON (ll) or START (lll),
battery voltage is applied to lhe windshield
wiper/washer switch, and the windshield wiper
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 wiper
switch at G401, and the wipers run at low speed.
ParUOfi
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 ol the windshield wiper motor are
grounded through the BLUI/EL 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 (lntermittenvPark 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 returns 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.
91-2
Mist
When you pull the wiper switch down to MIST
position, the high speed windings of the wiper motor
are grounded through the BLU//EL wire and the
closed contacts of the mist switch at G401, and the
wipers make one pass across the windshield at high
speed. The PABKOFF tunction then takes over and
the wrpers stop in the PARK position.
Washer
When you pull the wiper switch toward you to turn on
the washer switch, battery voltage is applied to the
washer motor. The motor pumps fluid onto the
windshield until you release the lever. On models
with combined wiper/washer operation (Canada), the
integrated control unit (windshield washer ON input)
senses power al the BLI(GRN wire terminal and
runs the washer motor whenever the wioers run.
Reter to the Service irlanual (Section 23, Electrical)
for specific tests or troubleshooting procedures.