2003 HONDA CIVIC switch

lmmobilizer System
Troubleshooting (cont'dl
8. Check for voltage betvveen the immobilizer control
unit-receiver 7P connector No. 6 terminal and No. 1
rermlnat.
ls thete battery voltage?
YES Go to step 12.
NO Check for these problems,
. Open on the BRNI/EL wire.l. Faulty ECM.I
9. Remove the driver's dashboard lower cover (see
page 20-59).
10. Remove the steering column lower cover (see page
17-9).
11. Disconnect the 7P connector (A) from the
immobilizer control unit-receiver (B).
22-166
-
Check for continuity between the immobilizer
control unit-receiver 7P connector No. 2 terminal
and ECM terminal E27.
ls there continuity?
YES-Go to step 13.
NO- Repair the open in the RED/BLU wire.I
Reconnect the 7P connector to the immobilizer
control unit-receiver.
Check for voltage between the immobilizer control
unit-receiver 7P connector No. 4 terminal and body
ground with the parking brake lever pulled, then
released.
ls there 1 V or less, then 5 V or more?
YES Replace the immobilizer control unit-receiver.
After replacing the immobillzer control unit-
receiver, rewrite the unit with a Honda PGM
Tester.l
NO Check for these problems:
. Faulty parking brake switch or a poor body
ground of the parking brake switch.l. Repair short or open in the GRN/ORN wire. I
13.
14.
{

ICircuit Diagram
' I'10.20 {a0AJ :usAib.a)l50A) :C.nd.IGNITiON SWITCH
/ BAI \--_to oJ- BLI,'YEL tcl ./
J
G201
HAICIILATCHSWITCH
{cont'd)
UiIDM HOOD IUSE/NEUY BOX
MULTIPLEXc0NT80rtNsPECTror!CONNECIOF
UNDEf, DASHFUSE/NEUYBOX
22-169

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.
22-172
-
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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CavitvWireTest conditionTest: Desired resultPossible cause if resuk is not obtainedX8WHT/BLKUnder allconditionsAttach to ground:The ignition keylight should come on.Blown No.3 (7.5A)fuse in the under,hood
Blown LEDAn ooen in the wireo7GRN/REDCeiling light switch inthe middle position,all doors closed
Attach to ground:The ceiling light,spotlights should come on.Elown No. 3 (7.54)fuse in the undeFhood
Faulty ceiling lightAn oDen in the wirec]1BLU Under all conditionsAttach to ground: Dash lights shouldBlown No. 2 (15Aifuse in the under-hoodfuse/relay boxFaulty taillight relayAn ooen in the wireF8GRN/REDBrake fluid reservoirfloat in downposition (brake fluid
Check for voltage to ground:There should be less than I V.Faulty brake fluid level switchAn open in the wire
Brake lluid reservoirfloat in up position(brake fluid at fulllevel)
Check for voltage to ground:There should be 5 V or more.Faulty brake fluid level switchShortto ground
E10YELUnder all conditionsCheck for voltage to ground:There should be battery voltage inthe sleep mode and 3 Tvoltswhen
. An open or short in the wire
K10WHT/GRNUnder all conditionsCheck for voltage to ground:There should be battery voltage inthe sleep mode and 3 Tvoltswhen
An open or short in the wire
22-177

Seat Belts
Front Seat Belt Replacement (cont'd)
Seat Belt Buckle
1. Make sure you have the anti-theft code for the radio,
then write down the frequencies for the preset
buttons.
2. Disconnect the negative cable from the battery ,and wait at least 3 minutes before beginning work.
3. Remove the front seat (see page 20-7'1).
4. Detach the seat belt switch connector clip (A), seat
belt buckle tensioner connector clip (B), and
harness clip (C).
5. Remove the center anchor bolt (A), and remove the
seat belt buckle {B).
7/16-20 UNF32 N m {3.3 kgf m,24lbf.ft)
6. Pullthe seat belt switch/tensioner harness (C) out
through the hole on the seat track.
. -.. :.a--
23-6
7. Installthe buckle in the reverse order of removal,
and note these items:
. Assemble the washers on the center anchor bolt
as shown.. Apply liquid thread lock to the center anchor bolt
before reinstallation.. lf the seat belt tensioner has been deployed,
replace the front seat belt protector with a new
one.. Apply liquid thread lock to the seat mounting
bolts before reinstallation. Reconnect the negative cable to the battery.. Enter the anti-theft code for the radio, then enter
the customer's radio station presets.. Reset the clock.. Do the ECMiPCM idle learn procedure (see page
1 1_139).
COLLAR

sRs
Precautions and Procedures
General Precautions
Please read the following precautions carefully beforeperforming airbag system service. Observe theinstructions described in this manual. or the airbags
could accidentally deploy and cause damage or injuries.
. Except when performing electrical inspections.
always turn the ignition switch OFF, disconnect the
negative cable from the battery, and wait at least 3minutes before beginning work.
NOTE: The memory is not erased even if the ignition
switch is turned OFF or the battery cables are
disconnected from the battery.. Use replacement pans which are manufactured to the
same standards and quality as the original parts. Do
not install used SRS parts from another vehicle. Useonly new pans when making SRS repairs.. Carefully inspect any SRS part before you install it.
Do not install any part that shows signs of being
dropped or improperly handled, such as dents, cracks,
or deformation.
. Before removing any SRS parts (including the
disconnection of connectors), always disconnect the
SRS connector.. Use only a digital multimeter to check the system. lf itis not a Honda multimeter, make sure its outout is 10mA (0.01A) or less when switched to the lowest value
in the ohmmeter range. A tester with a higher output
could cause accidental deployment and possible
injury.. Do not put objects on the front passenger's airbag.. The original radio has a coded theft protection circuit.
Be sure to get the customer's radio code and write
down the frequencies for the radio's preset stations
before disconnecting the battery cable.. Before returning the vehicle to the customer, enter
the radio code. then enter the customer's radio
station presets, and set the clock. Do the engine
control module (ECM) idle learn procedure (see page
11-139).
23-14
c
Steering-related Plecautions
Cable Reel Alignment
. Misalignment of the cable reel could cause an open in
the wiring, making the SRS system and the horns
inoperative. Center the cable reel whenever the
following is performed (see step 6 on page 23-121).
- Installation of the steering wheel- Installation of the cable reel- Installation ofthe steering column- Other steering-related adjustment or installation
. Do not disassemble the cable reel.
. Do not apply grease to the cable reel.
. lf the cable reel shows any signs of damage or
contamination. replace it with a new one. For
example, it does not rotate smoothly.