2003 HONDA CIVIC Workshop Manual

lmmobilizer System
Component Location Index
INOICATOR LIGHTBulb Replacement, page 22 63ECMReplacement, page 11-4Substitute known-good for testing,page 11-5
IMMOBILIZER CONTROL UNIT.RECEIVERTroubleshooting, page 22-165Replacement, page 22-167
TRANSPONDER(8uilt into the ignition key)
22-162

System Description
The vehicle is equipped with an immobilizer system that will disable the vehicle unless the proper ignition key is used.This system consists of a transponder located in the ignition key, an immobilizer control unit-receiver, an indicatorlight, and the ECM.
When the key is inserted in the ignition switch and turned to the ON {ll) position, the immobilizer control unit-receiversends power to the transponder in the ignition key. The transponder then sends a coded signal back to the immobilizer
control unit-receiver which then sends a coded signal to the ECI\4.
iEl'JUiliii'tlun"oona"|.r KEYCYLTNDER
lf the proper key has been used, the immobilizer indicator light will come on for about 2 seconds, then go off.lf the wrong key has been used or the code was not received or recognized by the unit, the indicator light will comeon for about 2 seconds, then it will blink until the ignition switch is turned OFF.lf the ignition switch is turned OFF, the indicator will blink for about 5 seconds to signal that the unit has reset
correctly, then the indicator will go off.
lf the customer has lost his key, and cannot start the engine, contact Honda Customer Relations.
IMMOBILIZER INDICATOR LIGHT BLINKING PATTERN:
IGNITION SWITCHON
OFF
PROPER KEYINSERTEDINDICATORLIGHTON
WRONG KEYINSERTEDINDICATORLIGHTON
OFF
(| i.,
IMMOBILIZER CONTROL UNIT.RECEIVER
)
22-163

lmmobilizer System
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UNDTR rcOD FUSE/RELAY 8OX
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EC
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Circuit Diagram
FGN
8ELAY1
YEUBIJ(
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DATA . PA8(II'IGLIN( SMIGCONNECIOR SWITCH{0Lcl .8nA{EFTUIDI!VELSWTfi
22-164
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I
Troubleshooting
Before troubleshooting the immobilizer system,
troubleshoot any EClvl Diagnostic Trouble Codes (DTCS)
(see page 11-3), and make sure the ECM has no
malfunction.
Note these items before trou bleshooting:
. Due to the action of the immobilizer system, the
engine takes slightly more time to start than on a
vehicle without an immobilizer system.. When the system is normal, and the proper key is
inserted, the indicator light comes on for 2 seconds,
then it will go off.. If the indicatorstartsto blink after 2 seconds, or if the
engine does not start. remove any other immobilizer
keys or large key fobs on the key ring, then repeat the
starting procedure.
lf the engine still does not start, continue with thisprocedure.
1. Turn the ignition switch ON {ll) with proper key.
2. Check to see if the immobilizer indicator light
comes on.
Does the indicator light blink?
YES Disconnect the 7P connector from the
immobilizer control unit-receiver, then go to step 9.
NO Check for these problems, then go to step 3.
. Blown No. 9 (10A)fuse in the under-hood
fuse/relay box.I. An open in the wire between the gauge assembly
and the immobilizer control unit-receiver.l. A faulty immobilizer indicator light,I. An open in the wire between the gauge assembly
and the under-hood fuse/relay box.l
Remove the driver's dashboard lower cover (see
page 20-59).
Remove the steering column lower cover (see page
11-9).
l
-_--t
22-165
5. Disconnect the 7P connector (A)from the
immobilizer control unit-receiver (B),
Check for voltage between the immobilizer control
unit-receiver 7P connector No. 7 terminal and body
ground.
ls there battery voltage?
YES-Go to step 7.
NO Check for these problems;
. Blown No. 9 {10A)fuse in the under-hood fuse/
relay box.l. An open in the WHT/RED wire.l
Check for voltage between the immobilizer control
unit-receiver 7P connector No. 6 terminal and bodyground with the ignition switch ON {ll).
ls there battery voltage?
YES- Go to step 8.
NO Check for these problems:
. Blown No.6 (15A)fuse in the under-hood
fuse/relay box,I. Faulty PGM-Fl main relay 1,t. An open in the YEUBLK wire.l
1.
(cont'd)

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.
{

t
2.
3.
lmmobilizer Control Unit-Receiver Replacement
'LRemove the driver's dashboard lower cover (see
page 20-59).
Remove the steering column covers (see page 17-
Disconnect the 7P connector (A) from the
immobilizer control unit-receiver (B).
5.
Remove the two screws and the immobilizer
control unit-receiver from the ignition key cylinder(c).
Install the immobilizer control unit-receiver in the
reverse order of removal.
After replacement, rewrite the unit with a Honda
PGM Tester, then check the immobilizer system.
JI
6.
-___-l-
22-167

Multiplex Control System
Component Location Index
IGNITION KEY LIGHTTest, page 22'91
lr, J
REAR CEILING LIGHTTest, page 22'96
LIGHT/SPOTLIGHTSTest, page 22-96
GAUGE ASSEMBLY
ECM
MULTIPLEX CONTROL UNIT{Built into the under-dashfus6/relav boxlTroubleshooting, page 22'172Input Test, page 22-175
22-168
t

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