2003 HONDA CIVIC seat

Ground Distribution
Ground to Components Index
GroundComponent or circuit qrounded
Batterv, Transmission housinq
E ngine
G 101ECM (PG is BLK; LG is BRN/YEL)
BLK: IAC valve, lgnition coils, Vehicle speed sensor, VTEC solenoid valve
BRNA/EL: Camshaft oosition (CMP) sensor. CKP sensor, TDC sensor. VTEC oil pressure switch
G 15']EPS control unit
G201ELD unit. Multiplex control inspection connector, Multiplex control unit, Power window relay, Rear
window washer motor, Right front parking light, Right front side marker light, Right front turn signal
light, Turn signal/hazard relay, Washer fluid level sensor (Canada) , Windshield washer motor,
Windshield wiDer motor
G202ABS modulator-control unit
G301
G401
Blower motor relay, Brake fluid level switch, Condensor fan motor, Cruise control actuator, Left front
parking light, Left front side marker light, Left front turn signal light, Radiator fan motor, Radiator fan
swrtcn
Combination liqht switch, lqnitlon kev srvitch, Wiper/wasfrer sr,virch
G402Left and riqht airbaq sensors, SRS unit
G 451Data link connector (DLC)
G501Clutch interlock switchm Clutch pedal position switch (for cruise control), Cruise control main switch,
Cruise control unit, Daytime running lights control unit (Canada), Driver's door lock knob switch,
Driver's door lock switch, Driver's power window motor, Heater control panel, Left power mirror
defogger (Canada), left side turn signal light, Moonroof control unit, Monroof open and close relays,
Moonroof position sensor '1, Moonroof seitch, Power mirror switch, Power transistor, Power window
master switch. SDotliqhts
G502Accessory power socket, Gauge assembly, Keyless receiver unit, lvlultiplex control unit, Right power
mirror defogger {Canada)
G503Audio unit
G551Driver's seat belt switch, Fuel gauge sending unit, Fuel pump, Memory erase signal (IMES) connector,
OPDS unit. Rioht seat belt switch
G552High mount brake light, License plate lights, Rear window defogger, Rear window defogger noise
condenser. Rear window wioer motor, Hatch latch switch
Back-up lights, Brake lights, Rear side marker lights, Rear turn signal lights, Rear window wiper noise
condenser, Rear window wiper intermittent control unit, Taillights
22-48

Gauges
Self-diagnostic Procedure
The gauge assembly has a self-diagnosis function.. The Beeper Drive Circuit Check. The Indicator Drive Circuit ChecL. The LCD Segments Check. The Gauges Drive Circuit Check (Speedometer, Tachometer, Fuel gauge, Coolant temperature gauge). The Communication Line Check (the coolanttemperature signal line between the gauge and ECM)
NOTE: Indicators are also controlled via the communication line.
Entering the self-diagnosis f unction:
Before doing the self-diagnosis function, check the No. 9 (10A) fuse in the under-hood fuse/relay box and No. 10 {7.5A)fuse in the under'dash fuse/relay box.
1. Push and hold the trip/reset button.
2. Turn the lighting switch ON.
3. Turn the ignition switch ON (ll).
4. Within 5 sec., turn the lighting switch OFF, then ON and OFF again.5. Within 5 sec., release the trip/reset button, then push and release the button four times reDeatedlv.
NOTE:. While in the self-diagnosis mode, the dash lights brightness controller operates normally.'Whileintheself-diagnosismode,thetrip/resetbuttonisusedtostartthebeeperdrivecircuitcheckandthegauge
drive cicuit check.. lf the vehicle speed exceeds 1.2 mph 12 km/h) orthe ignition switch is tu rned OFF, the self,diag nosis mode ends.
oN flrl
lgnition
Switch
Lighting
Switch
Trip/Reset
Switch-> Move to selt-diagnosis mode.
5 sec.5 sec.
The Beeper Drive Circuit Check:
When entering the self-diagnosis mode, the beeper sounds five times
The Indicator Drive Circuit Check:
When entering the self-diagnosis mode, the following indicators blink.
Seat belt indicator, Door/hatch indicator, Brake system, Lowfuel indicator, Maintenance required indicator (USA),
Washer fluid level indicator (Canada), Oil pressure light.
v
OFF
22-56

Exterior Lights
Headlight Adjustment
Before adiusting the headlights:. Park the vehicle on a level surface.. Make sure the tire pressures are correct.. The driver or someone who weighs the same should
sit in the driver's seat.
'1. Clean the outer lens so that you can see the center
of the headlights (A).
Headlights become very hot during use; do not
touch them or any attaching hardware immediately
after they have been turned off.
22-78
7.5 m {25 ftl
\
2. Park the vehicle 7.5 m (25 ft) away from a wall or a
screen (A).
3. Open the hood.

ISystem Descriptions
The Multiplex Control System has four internal
functions:. Multiplexing (send multiple signals over sharedwtres). Wake up/sleep (runs at full power only on demand toreduce battery draw). Fail-safe (fixes or ignores faulty signals). Self-diagnosis (Mode 1 for the system, Mode 2 for
input lines)
The system controls the function of these circuits:. Entry lightcontrol (ignition key lightandceiting light). Wiper/washer intermittent wipe and park functions. Keyless/power door lock. Meter assembly, temperature gauge, and indicator
lights. HVAC (compressor and fan control). Key-in reminder. Headlight reminder. Seatbelt reminder
JI
/ar
22-171
Multiplex Communication
To reduce the number of wire harnesses, digital signals
are sent via shared multiplex communication linesrather than sending normal electrical signals throughindividual wires.. The input signals from each switch are converted todigital signals at the central processing unit (CpU).. The digital signalsaresentfromthetransmitting unitto the receiving unit as serial signals.. The transmitted signal is converted to a switch signalat the receiving unit, and it operates the related
component or monitors a swltch.. There are exclusive communicalion lines between
the ECM, the gauge assembly, and the under,dash
fuse/relay box.
Wake-up and Sleep
The multiplex control system has "wake-up" and"sleep" functions to decrease parasitic draw on the
battery when the ignition switch is OFF.. ln the sleep mode, the multiplex control unit stops
functioning (communication and CPU control) when it
is not necessary for the system to operate.. As soon as any operation is requested (for example, adoor is unlocked), the related control unit in the sleep
mode immediately wakes up and begins to function.. When the ignition switch is turned OFF, and the
driver's or front passenger's door is opened, then
closed, there is about a 10 second delay before the
control unit goes from the wake-up mode to the sleepmode.. lf any door is open, the sleep mode will not function.. lf a key is in the ignition switch, the sleep mode will
not function.. When in sleep mode, the draw is reduced from
70 80 mA to less than 10 mA.
Fail-safe
To prevent improper operation, the multiplex controlsystem has a fail-safe function. In the fail-safe mode,
the output signal js fixed when any part of the systemmalfunctions (for example a faulty control unit orcommunication line).
Each control unit has a hardware fail-safe function thatfixes the output signal when there is any CPUmalfunction, and a software fail-safe function thatignores the signal from the malfunctioning control unitand allows the system to operate normally.

Multiplex Control System
Troubleshooting
Mode 1 Tset
1. Remove the driver's dashboard lower cover {see
page 20-59).
2. Check the No. 9 ( 10A) fuse in the under-hood fuse/
relay box and the No. 10 (7.5A) fuse in the under-
dash fuse/relay box.
Are the fuses OK?
YES-Go to step 2.
NO-Find and repairthe cause ofthe blown fuse.!
3. Turn the ignition switch ON (ll).lf the driver's
seatbelt is unbuckled the seat belt reminder will
chime 6 times.
4. Set the ceiling light to the center position and close
allthe doors.
5. Connect the specialtoolto the multiplex inspection
conneclor.
6. After about 5 seconds the spotlight and ceiling light
should come on for 2 seconds, go out, then blink on
for 0.2 second to show the system is now in mode
1.
Did the spotlight and ceiling light indicate mode
1?
YES-Go to step 8.
NO Go to step 7.
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-
7. Check for continuity between terminal 4ofthe
under-dash fuse/relay box connector J and body
ground.
ls there continuity?
YES Replace the under-dash fuse/relay box.l
NO - Repair the open in the wire.lf the wire is ok,
repair G301.1
8. lf ther are any DTCS present, the spotlight and
ceiling light will blink to indicate the DTC(S). lf more
than one DTC is present, the DTCS will be displayed
in ascending order, lf there are no DTCS the
spotlight and ceiling light will not blink again after
the mode 1 indication.
Are there any DTCg?
YES Go to step 9.
NO Go to the Mode 2 test.
9. Troubleshoot the DTC(S) in the order indicated
using the following charts.
lf a faulty control unit is suspected, substitute it
with a known food part and recheck for DTCS,
. lf the DTC(s) isstill present. go to the next step
listed for the DTC.. lf the DTC(S) is no longer present replace the
original part.

Multiplex Control System
Multiplex Control Unit lnput Test (cont'd)
3. Inspect the connector and socket terminals to be sure they are all making good contact
.lftheterminalsarebent,looseorcorroded,repairthemasnecessary,andrecheckthesystem. llthe terminals look OK, go to step 4.
4. Reconnectthe connectorstothe under dash fuserelay box, and make surethese inputtests atthe appropriate connectors on lhe under-
dash fuse/relav box.
. lf any test indicates a problem, {ind and correct the cause, then recheck the system. lf allthe input tests prove OK, the multiplex control unit must be faulty. Replace the under_dash fuse/relay box assembly
CavitvWireTest conditionTest: Desired .esult r Possible cause if resullE qS!q!!e!!ed
J4BLK[J nder all conditionsCheck {or voltage 1o ground:Therc sholl.l he 1V or lessPoor ground (G20'l)An ooen in the wire
Y6BLKlJnder all conditionsCheck for voltage to ground:There should bc 1 V or less.Poor ground 1G501)An ooen in the wire
Y1BFNryELParking brake leverdown, turn theigntion switch ON (ll)
Check for voltage to ground:There should be battery voltagewhile the Brake system indicator ison forthe buld check.
An open in the wireShortto groundFaulty ABS modulatorcontrol unit
Check for voltage to ground:There should be 1V or less when the
J2WHT/REDUnder allconditionsCheck for voltage to groundiThere should be baftery voltage.Blown No.9 (10A)fuse in the under'hoodfuse/relay boxAn oncn in rhc wire
CavitvTest conditionTesi: Oesired resultPossible cause ifresult is notobtained
o3GRNDriver's door openCheck for voltage to ground:There should be 1 V or less-Faulty driver's door switchAn ooen in the wire
Driver's door closedCheck for voltage to ground:There should be 5 V or more.Faulty driver's door switchShort to qround
O4LT GRN/REDPassenger's doorCheck .for voltage 10 ground:There should be 1 V or less.Faulty passenger's door switchAn ooen inthewire
Passenger's doorCheck for voltage to ground:There should be 5 V or more.Faulty passenger's door switchShort to oround
osI]l.l
4.,
F1
F8
GRN/ORN
GRN/ORN
GRN/RED(USA)GRN/ORN(Canada)
Parking brake leverCheck for voltage to groLrnd:There shorl.l be 1 V or less.Faulty parking brake switch. An ooen in thewireCheck for voltage to ground:There should be 5 V or more.
. Faulty parking brake switchShortto ground
o5BLU/REDlgnition switch ON (ll),
driver's seat belt isCheck for voltage to ground:There should be 1V or less.Faulty driver's seat belt switchPoorground (G551)An oDen in the wire
Q6BLU/REDlgnition switch ON (ll)
driver's seat belt isbuckled.
Check {or voltage to ground:There should be 6 V or more.Faulty driver's seat belt switchShortto ground
P18RED
H",=
Check for voltage to ground:There sho0ld be 1V or less-
f -9*:li:'^:**:':s*:*
Faulty hatch latch swrtchPoor ground (G552)An open in the wireFaulty hatch latch switch
X5lgnirion key in the Check for voliage to gtound:ignit on switch Thpre should be I V or lcss
lgnrtron kev our o{ the Check for vollage to ground:
. Faulty ignition key switch. Poor ground (G401). An open in the wire
I : [11y.'::i':::1"' **6
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Restraints
Restraints
Special Tools ............. 23-2
Seat Belts
Component Location Index ......................................... 23-3
Front Seat Belt Replacement ....................................... 23-4
Rear Seat Belt Replacement ........................................ 23-6
Inspection .................. 23-8
Child Seat Tether Anchor Removal/lnstallation ........ 23-9
SRS (Supplemental Restraint Systeml
Component Location Index ......................................... 23-13
Precautions and Procedures ,,.,......... 23-14
General Troubleshooting Information ....................... 23-23
DTC Troubleshooting Index .............. 23-28
Symptom Troubleshooting Index ............................... 23-30
System Description ................. ........... 23-31
Circuit Diagram ......... 23-34
DTC Troubleshooting ............... .......... 23-36
SRS Indicator Circuit Troubleshooting ....................... 23-105
Component R e place me n(/ln s pect io n After
Deployment ..............23-112
Driver's Airbag Replacement ............ 23-113
Front Passenger's Airbag Replacement ..................... 23-1 14
Side Airbag Replacement .................. 23-115
Airbag Disposal ....................... ........... 23-116
Cable Reel Replacement .................... 23-119
SRS Unit Repfacement ....................... 23-122
Side fmpact Sensor Replacement ..........,.................... 23-123
OPDS Unit Replacement .................... 23-124
Front fmpact Sensor Replacement .............................. 23-125

Seat Belts
IComponent Location Index
CHILD SEATTETHERANCHORSRemoval/lnstallation,page 23-11
REAR CENTER BELT andREAR SEAT BELT BUCKLESstep 1 on page 23-8Inspection, page 23 9
SHOULDERANCHOR ADJUSTERstep 8 on page 23-4
FRONT SEAT BELTReplacement, page 23-4Inspection, page 23 9
I
REAR SEAT BELTBeplacement, page 23.7Inspection, page 23-9
FRONT SEATBELT BUCKLESstep 1 on page 23'6
23-3