2003 HONDA CIVIC radiator fan

Fan Controls
Component Location Index
RADIATOR FAN RELAY
RADIATOB FAN SWITCHTest, page 10'17Replacement, page'10-17
UNDER.HOODFUSE/RELAY BOX
RADIATOR FAN ASSEMBLYMotor Test, page 10 4
CONDENSER FAN ASSEMBLYMotor Test, page 10-4
10-11

Fan Controls
Symptom Troubleshooting Index
Before performing any troubleshooting procedures check:. Fuses. Grounds. Cleanliness and tightness of all connectors
\{
\,4
SYMPTOMPROCEDURE
Radiator fan does not run at allRadiator Fan Circuil Troubleshooting (see page 1O-14).
Radiator fan does not run for engine cooling, but it runswith A,/C ON
Radiator Fan Switch Circuit Troubleshooting (Open)
(see page 10-16).
Radiator fan runs with ignition switch ON (ll), Ay'C OFF,
and engine temperature below 199"F (93"C)Radiator Fan Switch Circuit Troubleshooting (Short)
(see page 10-'16).
10-12
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Fan Gontrols
Radiator Fan Circuit Troubleshooting
1. Check the No. 4 (20A) fuse in the under-hood
fuse/relay box, and the No. 14 (10A) fuse in the
under-dash fuse/relay box.
ls the tuse (s) OK?
YES-Go to step 2.
NO- Replace the fuse (s) and recheck.l
2. Remove the radiator fan relay from the under-hood
fuse/relay box, and test it (see page 22-51).
ls the relay OK?
YES Go to step 3.
NO Replace the radiator fan relay. t
3. Measure the voltage between the No. 2 terminal of
the radiator fan relay 4P socket and body ground.
RADIATOR FAN RELAY 4P SOCKET
Terminal side of female terminals
ls there battery voltage?
YES Go to step 4.
NO Replace the under-hood fuse/relay box. I
10-14
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(
4. Connect the No. landNo.2terminalsofthe
radiator fan relay 4P socket with a jumper wire.
RADIATOR FAN RELAY 4P SOCKET
JUMPERWIRE
Terminal side of Iemale terminals
Does the radiatot fan run?
YES Go to step 5.
NO Go to step 6.
Disconnect the jumper, and turn the ignition switch
ON { ll}. Check for voltage between the No. 3
terminal of the radiator fan relay 4P socket and
body ground.
BADIATOB FAN RELAY 4P SOCKET
Termlnal side of female terminals
ls there battety voltage?
YES-Go to step 9.
NO Check for an open in the wire between the
under-hood fuse/relay box and under-dash fuse/
relay box.l
\-

7.
Disconnect the radiator fan motor 2P connector.
Check for continuity between the No. 1 terminal of
the radiator fan relay 4P socket and the No. 2
terminal of the radiator fan motor 2P connector.
RAOIATOR FAN REI-AY 4P SOCKET
Terminal side offemale terminals
RADIATOR FAN MOTOR 2P CONNECTOR
ls thete continuity?
YES-Go to step 8.
NO Repair open in the wire between the under-
hood fuse/relay box and the radiator fan motor 2P
connector terminal No. 2,I
8. Check for continuity between the No, 1terminal of
the radiator fan motor 2P connector and bodv
g rou nd.
RADIATOR F
Wire side of female terminals
ls there continuity?
YES Replace the radiator fan motor.l
NO Check for an open in the wire between
radiator fan motor 2P connector terminal No. 1 and
body ground. lf the wire is OK, check for a poor
ground at G301.1
AN MOTOR 2P CONNECTOR
rftr
T-
Y
9.
10.
Reinstall the radiator fan relay.
Disconnect the radiator fan switch 2P connector.
Connect the No. 1 and No. 2 terminals, of the
radiator fan switch 2P connector with a jumper wire.
RAOIATOR FAN SWITCH2P CONNECTOR
11.
5\- IJUMPERf-; 'fl I wrRE
--
Wire side of female terminals
Does the radiator fan run?
YES- Replace the radiator fan switch.l
NO-Go to step 12.
Remove the jumper wire, and measure the voltage
between the No, 2 terminal of the radiator fan
switch connector and body ground,
RADIATOR FAN SWITCH2P CONNECTOR
ls there battery voltage?
YES Check for an open in the wire between
radiator fan switch 2P connector terminal No. 1 and
body ground. lf the wire is OK, check for a poor
ground at G301.1
NO Repair open in the wire between the radiator
fan switch terminal No. 2 and the under-hood
fuse/relay box.l
10-15

Fan Controls
Radiator Fan Switch Circuit
Troubleshooting (Openl
1. Disconnect the radiator fan switch 2P connector.
2. Turn the ignition switch ON (ll).
3. Measure voltage between the No.2 terminal ofthe
radiator fan switch 2P connector and body ground.
RADIATOR FAN SWITCH 2PCONNECTOR
ls there battety voltage?
YES-Go to step 4.
NO- Repair open in the wire between the radiator
fan switch 2P connector terminal No. 2 and under-
hood fuse/relay box.l
Turn the ignition switch OFF, and check for
continuity between the No. '1 terminal of the
radiator fan switch 2P connector and body ground.
RADIATOB FAN SWITCX 2PCONNECTOR
ls there continuity?
YES Replace the radiator fan switch. t
NO Check for an open in the wire between theradiator fan switch 2P connector terminal No. 1 and
body ground. lf the wire is OK, check for a poor
ground at G301.1
10-16
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Radiator Fan Switch Circuit
Troubleshooting (Short)
NOTE: After troubleshooting, perform the engine
control module (ECM)idle learn procedure (see page
1 1,139).
1. Remove the radiator fan relay from the under-hood
fuse/relay box, and test it (see page 22-51).
ls the relay OK?
YES Go to step 2.
NO Replace the radiator fan relay.I
2. Remove the radiator fan switch, and test it (see
page 10-17 ).
Is the radiatot tan switch OK?
4.
YES Go to step 3.
NO Replace the radiator fan switch.I
Disconnect the battery negative cable from the
battery.
Disconnect engine control module {ECM) connector
B (24P) and the under hood fuse relay box 14P
connector.
Check for continuity between the No. 2 terminal of
the radiator fan switch 2P connector and bodygrouno.
RADIATOR FAN SWITCH2P CONNECTOR
lstnere continuity?
YES Repair short in the wire between the radiator
fan switch 2P connector terminal No. 2 and under-
hood fuse/relay box.l
NO Replace the under-hood fuse/relay box.t
\I
\

Radiator Fan Switch Test
NOTE: Bleed air from the cooling system after installing
the radiator fan switch (see page 10-6).
1, Remove the radiator fan switch from the radiator
(see page 10-17).
2. Suspend the radiator fan switch (A) inacontainer
of water as shown.
3. Heat the water, and check the temperature with a
thermometer. Do not let the thermometer (B) touch
the bottom of the hot conlainer.
4. Measure the continuity between terminal No. 1 and
terminal No. 2 according to the table.
Termina
Operation lTemperature1
swtTcH
ON196" 203'F(91" gs"C)
OFF5' 15'F {3' 8'C) lowelthan the temoeraturewhen it goes on
Radiator Fan Switch Replacement
1.Disconnect the radiator fan switch connector, then
remove the radiator fan switch (A).
A24 N m (2.4 kgt.m, 17 lbt.ftl
2. Installthe radiator fan switch with a new O-ring (B).
10-17

Wire side o{ female terminals
NOTE: Standard baftery voltage is 12 V.
Terminalnumo€tWire color[erminal nameDescriptionSignal
BLUAvHTVTC+ lVTC OIL CONTBOLSOLENOID VALVE +SIDE)Drives VTC oilcontrolWith ignition switch ON (ll): 0 V
2lNJa {No. 4INJECTOR)Driveso. 4 iniectorAt idle: duty controlled
3BLJo.3INJECTORIDriveso.3 iniector4R1)TOR)Driveso.2 iniector
5BRNlNJl 1No. I INJECTOR)Drives No. 1 iniector
6GRNFANC (RAOIATOR FANCONTROL)Drives radiator fan relayWith radiator fan running: about 0 VWith radiator fan stopped: batterv voltaoe
7GRN/vVHTRVS (REVERSE LOCKSOLENOID VALVE)Drives reverse lock solenoidWith vehicle speed below 9.4 mph (15 km/h):battery voltageWith vehicle speed above 12.5 mph (20 km/h): 0 V
8REDAVHTECT (ENGINE COOLANTTFMPFRATURE SENSOR)Detects ECT sensor signalWith the ignition switch ON (ll): about 0.1 4.8 Videoendino on enoine coolant temDerature)
9BLU/BLKVTPSW (VTEC OILPRFSSTIRF SWITCH)Detects VTEc oil pressureswitch sionalWith engine at low engine speed: about 0 .Wirh enoine at hioh enoine soeed: batterv voltaqe
10WHT/BLUALTL (ALTEBNATOR LSIGNAI IDetects alternator L signalWith ignition swit'ch ON (ll): about 0 VWhh enoine runnino: batterv voltaqe
WHT/REDALTF (ALTERNATOR FRSIG NALIDetecls alternator FB signalWith engine running: about 0 V- 5 V{deoendinq on electrical load)
GRN/YELVTS {VTEC SOLENOIDDrives VIEC solenoid valveAt idle: about 0 V
'17REDI/ELIAT (INTAKE AIRTEMPERATURE SENSOR)Detects IAT sensor signalWith ignition switch ON {ll): about 0.1 V 4.8 vl.lcnen.iino on intake air temoerature)
18WHT/GRNALTC (ALTERNATOR
CONTROL)Sends alternator controlWith engine running: about 0 V 5 V(.lcocn.lino on electrical ioad)
21YEUBLUPCS {EVAPORATIVEEMISSION CANISTERPURGE VALVE)
Drives EVAPcanister purgevalveWith engine running, engine coolant below 149'F
165'C): battery voltageWith engine running, engine coolant above 149'F165"C): dutv controlled
23BLK/Vr'HTVTC (VTC OIL CONTROLSOI FNOID VALVE SIDE)Drives VTC oilcontrolWith the ignition switch ON (ll): 0 V
(confd)
11-21

DTC P0108: MAP Sensor Circuit High Voltage
'1. Start the engine. Hold the engine at 3,000 rpm with
no load (in neutral) until the radiator fan comes on,
then let it idle.
2. Check the MAP with the scan tool.
le about 101 kPa (780 nmHg, 30 in.Hg) ot highet,
or about 2.9 V or higher indicated?
YES Go to step 3.
NO-lntermittent failure, system is OK at this time.
Check for poor connections or loose terminals at
the MAP sensor and at the ECM.I
3. Turn the ignition switch OFF.
4. Disconnectthe MAP sensor 3P connector.
5, Connect MAP sensor 3P connector terminals No. 2
and No. 3 with a jumper wire.
MAP S€NSOR 3P CONNECTOR
MAP{GRN/REO}SG1 (GRN/WHTI
JUMPER WIRE
Wire side of female terminals
6. Turn the ignition switch ON (ll).
7. Check the MAP with the scan tool.
ls about 101 kPa (760 mmHg,30 in.Hg) ot higher,
or about 2.9 V or higher indicated?
YES-Go to step 8.
NO Replace the MAP sensor.I
8. Remove the jumper wire.
123
9. Measure voltage between MAP sensor 3P
connector terminals No. 1 and No. 3.
MAP SENSOR 3PCONNECTOF
vccl{YEL/RED) l,lo cll.l.rl
I lsct
d) l{GRN/wHrr
YIilll
Wire side of female lerminals
ls there about 5 V?
YES Go to step 10.
NO Repair open in the wire between the ECM
(A1 1 ) and the MAP sensor.I
Turn the ignition switch OFF.
Connect ECM connector terminals A11 and A19
with a jumper wire.
ECM CONNECTOR A {31PI
Wire side of fema e te.minals
Turn the ignition switch ON (ll).
Check the MAP with the scan tool.
ls about 101 kPa (760 mmHg, 30 in.Hg) or higher,
or about 2.9 V ot higher indicated?
YES Update the ECM if it does not have the lalest
software, or substitute a known-good ECM, lhen
recheck (see page 1 1-6). lf the symptom/indication
goes away with a known good ECM, replace the
original ECM.I
NO-Repair open in the wire betlveen the ECI\il
(A19) and the MAP sensor.I
10.
11.
JUMPER WIAE
11-53