2003 HONDA CIVIC Harness

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
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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.

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.
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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).
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Wiring Precautions
Some of the SRS wiring can be identified by a special
yellow outer covering, and the SRS connectors can be
identified by their yellow color.
Observe the instructions described in this section.
. Never attempt to modify. splice, or repair SRS wiring.
lf there is an open or damage in SRS wiring, replace
the harness.
Be sure to install the harness wires so they do not get
Dinched or interfere with other Darts.
Make sure all SRS ground locations are clean, and
grounds are securely fastened for optimum metal-to-
metal contact. Poor grounding can cause intermittent
problems that are difficult to diagnose.
Precautions for Electrical Inspections
. When using electricaltest equipment, insertthe
probe of the tester into the wire side of the connector.
Do not insert the probe of the tester into the terminal
side of the connector, and do not tamper with the
connector.
Use a U-shaped probe. Do not insert the probe
forcibly.
Use specified service connectors in tro u bleshooting.
Using improper tools cou ld cause an error in
inspection due to poor metal-to-metal contact.
(cont'd)
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sRs
Precautions and Procedures (cont'dl
Disconnecting System Connectors
Before removing a front airbag. side airbag, or other SRS related devices {the SRS unit, the cable reel, the front impact
sensors, the side impact sensors, the seat belt buckle tensioners, and the seat belt tensioner connector), disconnectingconnectors from related devices, or removing the dashboard or the steering column, disconnect the airbag connectorsor the side airbag connectors to prevent accidental deploVment.
Turn the ignition switch OFF, disconnect the negative cable from the battery, and wait at least 3 minutes before
beginning the following procedures.'BeforedisconnectingSRSunitconnectorA(1)fromtheSRSunit,disconnectthedriver'sairbag4Pconnector(3).
the front passenger's airbag 4P connector (4), the driver's seat belt tensioner 2P connector (6), and the frontpassenger's seat belt tensioner 2P connector (7).
. Before disconnecting SRS unit connector B (8) from the SRS unit, disconnect both side airbag 2P connectors (11. '12),
and both seat belt buckle tensioner 4P connectors (9, 10).. Before disconnecting the cable reel 4P connector (2), disconnect the driver's airbag 4P connector (3).'Beforedisconnectingthefloorwireharness4Pconnector(5),disconnectbothseatbelttensioner2Pconnectors
(6.7).
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1. Disconnect the battery negative cable, and wait at
least 3 minutes.
Driver's Airbag
2. Remove the access panel (A) from the steering
wheel, then disconnecl the driver's airbag 4P
connector (B)from the cable reer.
Front Passenger's Airbag
3. Disconnect the front passenger's airbag 4P
connector (A)from dashboard wire harness B.
Side Airbag
4. Disconnect both side airbag 2P connectors (Alfrom
the floor wire harness.
(cont'd)
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sRs
Precautions and Procedures (cont'd)
Seat Belt Tensioner
5. Disconnect both seat belt tensioner 2P connectors
(A) from the floor wire harness
Seat Belt Buckle Tensioner
6. Disconnect both seat belt buckle tensioner 4P
connectors (A).
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4
SRS Unit
7. Disconnect SRS unit connector A, SRS unit
connector B, and/or SRS unit connector C from the
SRS unit.

General Troubleshooting Information
DTC (Diagnostic Trouble Codesl
The self-diagnostic function of the SRS system allows it
to locate the causes of system problems and then store
this information in memory. For easier troubleshooting,
this data can be retrieved via a data link circuit.
. When you turn the ignition switch ON (ll), the SRS
indicator will come on. lf it goes off after 6 seconds,
the system is normal.. lf there is an abnormality, the svstem locates and
defines the problem, stores this information in
memory, and turns the SRS indicator on. The data
will remain in the memory even when the ignition
switch is turned off or if the battery is disconnected.. When you connect the Honda PG lM Tester to the 16P
data link connector (DLC)to short the SCS terminal,
and turn the ignition switch ON (ll). the SRS indicator
will indicate the diagnostic trouble code (DTC) by the
number of blinks.. When you connect the Honda PGM Tester to the 16P
data link Connector (DLC), you can retrieve the DTC in
the Honda Systems "SRS" menu.. After reading and recording the DTC, proceed with
the troubleshooting procedure for th is code.
Precautions. Use only a digital multimeter to check the system. lf
it's not a Honda multimeter, make sure its output is
10 mA (0.01A) or less when switched to the smallest
value in the ohmmeter range, A tester with a higher
output could damage the airbag circuit or cause
accidental airbag deployment and possible injury.. Whenever the ignition switch is ON (ll), or has been
turned OFF for less than 3 minutes, be careful not to
bump the SRS uniU the airbags could accidentally
deploy and cause damage or injuries.. Before you remove the SRS harness, disconnect the
driver's airbag connector. the front passenger's
airbag connector, both side airbag connectors, both
seat belt buckle tensioner connectors, and both seat
belt tensioner connectors.. Make sure the battery is sufficiently charged. lf the
battery is dead or low, measuring values won't be
correct.. Do not touch a tester probe to the terminals in the
SRS unit or harness connectors, and do not connect
the terminals with a jumper wire. Use only the
backprobe set and the Honda PGM Tester. Backprobe
spring loaded lock type connectors correctly.
Reading the DTC
When the SRS indicator is on, read the DTC using either
of the following methods:
PGM Tester "SRS" Menu Method:
Connect the Honda PGM Tester {A) to the 16P data link
connector {DLC)(B), and follow the Tester's Drompts in
the "SRS" menu.
lf the Tester indicates no DTC, no communication. DTC
3-6 to 3-'10, DTC 4-6 to 4-10, DTC 9-1, or DTC 9-2,
double-check by using the "SCS" menu method.
(cont'd)
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sRs
General Troubleshooting Information (cont'dl
Erasing the DTG Memory
Specisl Tool Required
SCS service connector 07PAz-0010100
To erase the DTC(S)from the SRS unit, use a Honda
PGM Tester {see lhe Honda PGfM Tester SRS Vehicle
System Supplement) or the following procedure.
1. Make sure the ignition switch is OFF.
2. Connect the SCS service connector {A) to the MES
2P connector (B). Do not use a jumper wire.
07PAZ-0010100
3. Turn the ignition switch ON (ll).
4. The SRS indicator will come on for about 6 seconds,
and then go off. Remove the SCS service connector
from the MES connector within 4 seconds after the
indicator goes off.
5. The SRS indicator will come on again. Reconnect
the SCS service connector to the MES connector
within 4 seconds after the indicator comes on.
6. When the SRS indicator goes off, remove the SCS
service connector from the MES connector within 4
seconds.
7. The SRS indicator will bllnk two times indicating
that the memory has been erased.
8. Turn the ignition switch OFF, and wait for '10
seconds.
9. Turn the ignition switch ON (ll) again. The SRS js
OK if the SRS indicator comes on for 6 seconds and
then goes off.
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Troubleshooting lntermittent Failures
lf there was a malfunction, but it doesn't recur. it will be
stored in the memory as an intermittent failure, and the
SRS indicator will come on.
After checking the DTC, troubleshoot as follows:
1. Read the DTC (see "Reading the DTC").
2. Erase the DTC memory (see "Erasing the DTC
Memory").
3. With the shift lever in neutral, start the engine, and
let it idle.
The SRS indicator will come on for about 6 seconds
and then go off.
Shake the wire harness and the connectors. take a
test drive (quick acceleration, quick braking,
cornering), turn the steering wheel fully left and
right, and hold it there for 5 to '10 seconds. lf the
problem recurs, the SRS indicator will come on.
lf you can't duplicate the intermittent failure, the
system is OK at this time.
4.