1999 HONDA CIVIC system description

System Description
Steering Gearbox
The rack-and-pinion type steering gearbox has a valve body unit incorporated with the pinion to control the steering fluidpressure. Steering fluid from the pump is regulated by a rotary valve in the valve body unit and is sent through the cylin,der line to the power cylinder, where hydraulic pressure is applied. The steering fluid in the other side of the power cylin,der returns through the cylinder line and valve body unit to the reservoii.
VALVE EODY UNIT
CYLINDER LINE
To RESERVOm +-From PUMP -;
POWER CYLINDER
Valve Body Unit
Inside the valve body unit is the valve, which is coaxial with the pinion shaft, and controls the steering fluid pressure. Thevalve housing is connected with the fluid line from the pump, the return line to the reservoir, and the two cylinder linesfrom the respective power cylinder. The pinion shaft is double - structured with the input shaft connected to the piniongear, both of which are interconnected with the torsion bar.
The pin inserted in the valve and the pinion shaft groove engage; this allows the pinion shaft to rotate together with thevalve. Because of this construction, the difference in angle in the circumferential direction between the input shaft and thevalve becomes larger according to the torsional strength of the pinion or steering resistance. However, maximum torsionbetween the shafts is regulated by the engaged splines of the shafts at the pin engagement section to hold the torsion barwithin the set value,
This allows the steering system to function as an ordinary rack-and-pinion type steering if the steering fluid is not pressur-
ized because of a faulty pump,
VALVE
Difforence in angle botwoon theinput shaft and pinion shsft
PINION SHAFT
lo
INPUT SHAFT
-l
a
17-20
INPUT SHAFT

Air Conditioning
Speciaf Tools ......'.....' 22-2
f f f ustrated f ndex ......................... ".......' 22-3
Wiring/Connector Locations'.........'.... 22'4
Description
Outfine ............ .......22-s
Circuit Diagram
'96 - 98 Models ......"..........".......'.... 22-6
'99 Modef """""""' 22-7
Troubleshooting
Symptom Chart ".'......""................. 22-8
Flowcharts
Condenser Fan .........".................,..'. 22-9
Compressor .....""" 22-12
A/C System .........'.22'17
A/C Thermostat
Test ........'.......' """'22'21
Relays
Test ....."'......... ..""'22-21
A/C Service Tips and Precautions ......22-22
A/C System Torque Specifications '...22-23
A/C System Service
Performance Test ... '."......... ".... ....'..22-24
Pressure Test Chart .................. .... "' 22-26
Recovery ...".........," 22-27
Evaporator
Replacement .....",' 22'24
Overhauf .....-.....""' 22'29
Compressor {SANDEN}
Repf acement ......'.' 22-30
fffustrated fndex ......"..................'.... 22'32
Cf utch Inspection ......... "............ ...... 22-33
Clutch Overhau I ........................ ....... 22-34
Thermal Protector Replacement .... 22-36
Relief Valve Replacement ......'..."". 22-36
Compressor (DENSO)
Repfacement ..""',' 22-37
lf lustrated Index ............................... 22-39
Clutch lnspection ............."'...... "'.... 22-40
Cf utch Overhaul .....................'......... 22-41
Ref ief Valve Replacement'..'......"'.. 22-42
A/C Compressor Belt
Adiustment ............22'43
Condenser
Repfacement .......,,22'44
A/C System Service
Evacuation ...,,,.......22-45
Charging '..........--'..22'46
Leak rest """""""'22-46

Description
Outline
The air conditioner system removes heat from the passenger compartment by circulating refrigerant through the system
as shown below.
BLOWER FAN
EVAPORATOR(Absorption of heati
EOUALIZING TUBE(Meters pressure andimproves the expansionvalve reaction time)
into the evaporator)CAPILLATY TUBE SENSING BULB
lControls the temPerature of the
ref rigerant leaving the evaporator
by metering the expansion valve)
/\
THERMOSTAT
A/C PRESSURE SWITCH
When the refrigerant is below
200 kPa (2.0 kgtcm',28 Psi)or above 3,200 kPa 132 kgflcm',
455 psi), the Ay'C pressure
switch opens the circuit to
the A,/C switch and stops the
EXPANSION VALVE(Meters the requiredamount of refrigerant
airconditioning to Protect the
compressor.
RECEIVER/DRYER(Traps debris, andremoves morsturel
THERMAL PROTECTOR
{Opens the comPressorclutch circuit when the
compressor temPeraturebecomes too high)
RELIEF VALVE(Relieves pressure at the
compressor when thepressure is too high)
(Radiation of heat)
I
f-r--; I
(Suction and comPression,
HIGH PRESSURE VAPOR
HtGH PRESSUBE LIOUID
LOW PRESSURE LIOUID
This car uses HFC-134a (R-134a) refrigerant which does not contain chlorofluorocarbons Pay attention to the following
service items:
. Do not mix refrigerants CFC-12 (R-12) and HFC-134a (R-134a)' They are not compatible'
. Useonlythe recommended polyalkyieneglycol (PAG) refrigerant oil designedforthe R-134a compressor (SANDEN: SP-
10; DENSO: ND_OIL8). Intermixing ihe re-commended (pAG) refrigerant oil with any other refrigerant oil will result in
compressor failure.
. All A,,ic system parts {compressor, discharge line, suction line, evaporator, condenser, receiver/dryer, expansion valve'
O-rings for joints) have to be proper for refrigerant R- 134a Do not confuse with R-l2 parts'
. Use a halogen gas leak detector designed for refrigerant R-134a
. R-12 and R-134a refrigerant servacing equipment are not interchangeable. Use only a recovery/recycling/charging station
that is u,L.-listed and is certified to meet the requirements of sAE J2210 to service R-134a air conditioning systems'
. Always recover the refrigerant R-134a with an approved recovery/recycling/charging station before disconnecting any
A,/C fitting.
S]
22-5

)
Troubleshooting
Sef f -dia gnostic Proctdurcs ............. 2+13
Reading the DTC .............................. 2+13
Erasing the DTC Mcnrory ................ 24-15
Troubleshooting h.ttnitt.nt
Failures ..............24-15
SRS U n it ldcntificrtion .................... 24- 1 6
Diagnostic Troublc Code (DTC)
Chart - '96 - 97 Models..."'."....... 24-17
Diagnostic Trouble Code (DTCI
Chart - '$ - 00 Models '.........""' 24'19
SRS lndicaror Light Wire
connections ...'.,24-25
Ff owcharts ........,,,,.24-26
Airbag
Repfacemant ...'.'...24-67
Disposaf .................24'70
Cable Reel
Repfacement .........24'72
SRS Unh
Repfacement ..'......24'76
l-l
-+
sRs
Supplemental Restraint System (SRSI
Speciaf Tools ... ...........24'2
Component/Wirin g Locations
fndex ................ ......24-3
Description ................ 24-5
Circuit Diagram ......." 24'6
Precautions/Procedures
Generaf Precautions ...............,,,,,,,.. 24-7
Airbag Handling and Storage .........24-7
SRS Unit Precautions ...................... 24-8
Inspection After Deployment ........' 24-8
Wiring Precautions ................... ....... 24'9
Backprobing Spring-loaded Lock
Connectors .......,24-9
Spring-loaded Lock Connectol ....,,. 24-10
Spring-loaded Lock Connector with
Built-in Short Contact ................. 24-10
Disconnecting the Airbag
Connector(sl .....' 24'11
Steering-related Precautions ...,.,.,,. 24'12

Description
)
The sRS is a safety device which, when used in coniunction with the seat belt, is designed to help protect the driver land
front passenger) in a frontal impact exceeding a certain set limit. The system consists of the sRS unit {including safing
sensor and impact sensor), the cable reel, the driver's airbag (and front passenger's airbag)
FRONT PASSENGEB'SAIRAAG
DRIVER'S AIRBAG
CABLE REEL
SRS UNtT
t
Operation
The main circuit in the SRS unit senses and judges the force of impact and, if necessary, ignites the inflator charge(s) lf
battery voltage is too low or power is disconnected due to the impact, the voltage regulator and the back-up power clrcult
resoectivelv will keep voltage at a constant level.
For the SRS to operate:
(1) The impact sensor must activate. and send electric signals to the mlcroprocessor'
(2) The microprocessor must compute the signals' and must send signals to the airbag inflator(s)'
{3) The inflator(s) must ignite and deploy the airbag(s)'
_"-_-l
Ir3B!#h i
!.. I
ffi,*
Self-diagnosis System
A self-diagnosis circuit is built into the SRS unit; when the ignition switch is turned ON (ll), the SRS indicator light comes
on and goes off after about six seconds if the system is operating normally
lf the liglt does not come on, or does not go off after six seconds, or if it comes on while driving, it indicates an abnormal-
ity in the system. The system must be inspected and repaired as soon as possible
For better serviceability, the memory will store the cause of the malfunctlon, and the data link circuit passes on the infor-
mation from the memory to the data link connector (DLC). This intormation can be read with the Honda PGM Tesler con-
nected to the DLC (16P).
l,
24-5

Gruise Control (cont'd)
- How the Circuit Works
The cruise control system uses mechanical and
electrical devices to maintain the car's sDeed at a
setting selected by the driver.
System Description
The cruise control unit receives command signals
from the crurse control main switch and the cruise
control SeVResume switch. With the ignition switch
in ON (ll) or START (lll), voltage is provided to the
cruise control main switch through fuse 14. When
you push the switch to ON, power is provided to the
cruise control unit and the brake switch.
The cruise control unit receives information about
operating conditions from the brake switch, the
vehicle speed sensor (VSS), and the clutch switch
(manual transmission) or the A,/T gear position
switch (automatic transmission). The cruise control
unit then sends signals to the cruise control actuator
which regulates the throttle position to maintain the
selected speed. The conlrol unit compares the
actual speed of the car to the selected speed. The
control unit then uses the result of that comoarison
to open or close the throttle.
The brake switch releases the system's control of
the throttle at the instant you press on the brake
pedal. The switch sends a signal to the control unit
by removing power from the normally closed brake
input (GRY wire), and providing power at the
normally open brake input (GRN/vVHT wire). The
control unit responds by allowing the throttle to
close. The clutch switch or the A,/T gear position
switch sends a "disengage" signal to the control unit
that also allows the throttle to close.
The cruise control system will set and automatically
maintain any speed above 25 mph (40 km/h). To set
it, make sure the main switch is on and the switch
indicator is on. Then, after reaching the desired
speed, press the SET switch. This sends a "set"
signal to the cruise control unit which, in turn,
controls the cruise control actuator to maintain the
set speed.
When you push the SET switch and the cruise
control system is on, the "cruise control" ON
indicator lights up.
34-4
(
You can cancel the cruise control system by
turning the main switch off . This removes power to
the control unit and erases the set speed from
memory. lf the system is disengaged temporarily
by the brake switch, or clutch switch, and the car's
speed is still above 25 mph, press the resume
switch: the car will automatically return to the
previously set speed.
For gradual acceleration without pressing the
accelerator pedal, push the RESUME switch and
hold it there. This will send an "acceleration" signal
to the control unit. When you release the switch, the
system will be reprogrammed for the new speed. To
slow the car down. oush the SET switch in and hold
it there. This sends a "deceleration" signal to the
control unit, causing the car to coast. When the
desired speed is reached, release the SET switch.
This reprograms the system tor the new speed.
Refer to the Service Manual (Section 23, Electrical)
tor specific tests or troubleshooting procedures.
(
a

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