2003 HONDA CIVIC Circuit

ABS Components
DTC Troubleshooting (cont'd)
DTC 81: CPU (Central Processing Unit)
1. Clear the DTC, then disconnect the Honda PGM
Tester.
2. Test-drive the vehicle.
Does the ABS indicator come on and is DTC 81
indicated ?
YES Replace the ABS modulator-control unit.l
NO-The system is OK at this time. t
19-52
ABS Indicator Gircuit
Troubleshooting
ABS indicator does not come on
1. Turn the ignition switch ON (ll), and watch the ABS
indicator.
Does the ABS indicator come on?
YES The system is OK at this time.I
NO Go to step 2,
Pull up the parking brake lever.
Does the btake system indicator come on?
YES Go to step 3.
NO Repair open in the indicator power source
circuit. lf necassary, substitute a known-good ABS
modulator-control unit, and recheck. I. Blown No, 10 (7.5A) fuse.. Open in the wire between the No. 10 (7.5A)fuse
and lhe gauge assembly,. Open circuit inside the fuse box.
Turn the ignition switch OFF.
Disconnect the ABS control unit 31P connector.
Turn the ignition switch ON (ll).
Does the ABS indicator come on?
YES-Check for loose terminals in the ABS control
unit 31P connector. lf necessary, substitute a
known-good ABS modulator-control unit, and
recheck.l
NO Go to step 6.
Turn the ignition switch OFF.
Remove the gauge assembly (see page 22-64).
3.
5.
6.
7.

8.
9.
Disconnect the gauge assembly connector A (22P).
Check for continuity between gauge assembly
connector A {22P) terminal No, 12 and body ground.
GAUGE ASSEMBLY CONNECTOR A (22P)
Wire side of female terminals
ls there continuity?
YES- Repair shon to body ground in the wire
between the gauge assembly and the ABS control
unit.l
NO Go to step 10.
Disconnect the gauge assembly connector B (22P).
Check for continuity between gauge assembly
connector B (22P) terminal No. 12 and body ground.
GAUGE ASSEMBLY CONNECTOR B (22PI
Wire side ol Iemale terminals
ls there continuity?
YES Check for loose terminals in the gauge
assembly connectors. lf the connectors are OK,
replace the gauge assembly.l
NO Repair open in the wire between the gauge
assembly and body ground (G501).1
'10.
11.
3.
ABS indicator does not go off
1. Checkthe No. 8 (20Alfuse in the under-hood fuse/
relay box, and reinstall the fuse if it is OK.
ls the fuse OK?
YES Go to step 2.
NO-Replace the fuse, and recheck. lf the fuse is
blown, check for a shon to body ground in this fuse
circuit. ll the circuit is OK, replace the ABS
modulator-control unit. I
Check the No. 11 (7.5A) fuse in the under-dash
fuse/relay box, and reinstall the fuse if it is OK.
ls the f use OK?
YES Go to step 3.
NO Replace the fuse, and recheck. If the fuse is
blown, check for a short to body ground in this fuse
circuit. lf the circuit is OK, replace the ABS
modulator-control unit. I
Disconnect the ABS control unit 31P connector.
Measure the voltage between terminal No. l8 and
body ground.
A8S CONTROL UNIT3lP CONNECTOR
ls there battery voltage?
YES-Go to step 5.
NO Repair open in the wire between the No. 8
(20A) fuse and the ABS control unit.l
(cont'd)
Wire side of female terminals
19-53

ABS Components
5.
6.
ABS Indicator Circuit Troubleshooting (cont'dl
Turn the ignition switch ON (ll).
Measure the voltage between the ABS control unit
31P connector termina I No. 15 and body ground.
ABS CONTROL UNIT 3IP CONNECTOR
Wire side of female terminals
Is there battety voltage?
YES-Go to step 7.
NO-Repair open in the wire between the No. 11(7.5A) fuse and the ABS control unit.I
Turn the ignition switch OFF.
Check for continuity between the ABS control unit
31P connector terminal No. 19 and body ground.
ABS CONTROL UNIT 31P CONNECTOB
Wire side ot Iemale terminals
ls there continuity?
YES Go to step 9.
NO-Repair open in the wire between the ABS
control unit and body ground (G202). t
9. Turn the ignition switch ON (ll).
1.
8.
19-54
10. Connect the ABS control unit3lPconnector
terminal No.20 and body ground with a jumper
wire.
ABS CONTROL UNIT 31P CONNECTOR
Wire side of female terminats
Does the ABS indicator go off?
YES-Check for loose terminals in the ABS control
unil 31P connector. lf necessary, substitute a
known-good ABS modulator-control unit, and
recheck.I
NO Go to step 1 1.
Remove the gauge assembly, and leave the
connectors connected. Connect the gauge
assembly connector A (22P) terminal No. '12 and
body ground with a jumper wire.
GAUGE ASSEMBLY CONNECTOR A (22P)
\'l '1.
Wire side of female terminals
Does the ABS indicator go off?
YES-Repair open in the wire between the gauge
assembly and the ABS control unit.I
NO-Check for loose gauge assembly connectors.
lf the connectors are OK, replace the printed circuit
board in the gauge assembly.l

21-2
z t-'5
z t-o
z t-o
21-8
21-9
21-10
21-11
21-14
z t- to
HVAC (Heating, Ventilation, and Air Gonditioningl
Heating and Air Conditioning
SpecialTools
Comoonent Location lndex ........
A/C Service Tios and
Precautions
A,/C Refrigerant Oil
ReDlacement
General Troubleshooting
lnformation
DTC Troubleshooting Index .......
Symptom Troubleshooting
1ndex..............
System Description .....................
Circuit Diagram
DTC Troubleshooting ..................
Recirculation Control Motor
CircuitTroubleshooting .......... 21-25
Heater Control Power and Ground
Circuits Troubleshooting ........ 21-27
Condenser Fan Circuit
Troubleshooting ...................... 21-28
Radiator and Condenser Fans
Common Circuit
Troubfeshooting ...................... 21-29
Compressor Clutch Circuit
Troubleshooting ...................... 21-30
A,/C Pressure Switch Circuit
Troubleshooting ...................... 21-32
Air Mix Control Motor
Test and Reolacement ............. 21-34
Mode Control Motor
Test and Replacement ............. 21-35
Recirculation Control Motor
Test and Reolacement ............. 21-36
Evaporator Temperature Sensor
Reolacement and Test ............. 21-31
Power Transistor Test ................. 21 -38
Heater Control Panel and
Push Switch Assemblv
Removal and Installation ........ 21-38
Dust and Pollen Filter
Reolacement ..21-39
Blower Unit Removal and
lnstallation ...... 21-39
Blower Unit Comoonents
ReDlacement ............................ 21-41
Evaporator Core
Reolacement ..21-42*Heater Unit/Core
ReDlacement ..21-43
Heater Valve Cable
Adjustment .....21-46
CompressorReplacement .......... 21-47
Comoressor Clutch Check .......... 21-48
Comoressor Clutch Overhaul ..... 21-49
Compressor Thermal Protector
Reo1acement ............................ 21-51
Comoressor Relief Valve
Reolacement ............................ 21-51
Condenser Reolacement ............ 21-52
Refrigerant Recovery .................. 21-53
System Evacuation ...................... 21-54
System CharginS ......................... 21-55
Refrigerant LeakTest .................. 21-56
A,/C Svstem Tests ........................ 21-57

DTC Troubleshooting Index
In case of multiple problems, the recirculation indicator will indicate only the DTC with the least number of blinks.
ln case of an intermittent failure, the heater control panel will store the DTC until the ignition is turned off.
DTC {Recirculation
Indication Blinks)
Detection ltemPage
7An open in the air mix control motor circuit(see paqe 21-16)
8A short ln the air mix control motor circuit(see Daoe 21-'16)
9A problem in the air mix control linkaqe, door, or motor(see paqe 21- 17)
10An open or shon in the mode control motor circuit(see oaqe 21-18)
11A problem in the mode control linkage, doors, or motor(see paqe 21191
12A problem in the blower motor circuit(see paqe 21-20)
13A problem in the EEPROM in the heater control panel;
the control oanel must be reolaced
(see page 21-38)
14An ooen in the evaDorator temDerature sensor circuit(see paqe 21-23)
A short in the evaDoralor temoerature sensor circuit(see oaqe 21-241
21-9

Heating and Air Conditioning
{
a
a
SvmptomDiagnostic procedureAlso check for
Recirculation control doors do not
change between Fresh and Recirculate
Recirculation Control Motor
Circuit Troubleshooting (see page
21 251
Cleanliness and tightness of all
connectors
Both heater and Ay'C do not workHeater Control Power and Ground
Circuits Troubleshooting (see
page 21-27)
Blown fuse No. '14 (10A) in the
under-dash fuse/relay box
Poor ground at G501
Cleanliness and tightness of all
conneclors
Condenser fan does not run at all (but
radiator fan runs with the Ay'C on)
Condenser Fan Circuit
Troubleshooting {see page 21-28)
. Poor ground at G301. Cleanliness and tightness of all
connectors
Both fans do not run with the A,/C onRadiator and Condenser Fans
Common Circuit Troubleshooting
(see page 21-29)
Blown fuse No. 1 (20A) and No.4
(20A) in the under-hood fuse/relay
box
Poor ground at G30l
Cleanliness and tightness of all
connectors
Compressor clutch does not engage(both fans run with A,/C on)
Compressor Clutch Circuit
Troubleshootinq (see Daqe 21-30)
Cleanliness and tightness of all
connectors
A/C system does not come on (both
fans and compressor)
Ay'C Pressure Switch Circuit
Troubleshooting (see page 21-32)
Blown fuse No. 1 (20A) and No. 4
(20A) in the under-hood fuse/relay
box
Poor ground at G301
Cleanliness and tightness of all
connectors
\Symptom Troubleshooting Index
\
21-10
!

Heating and Air Gonditioning
System Description (cont'dl
The air conditioning system removes heat from the passenger compartment by circulating refrigerant through the
system as shown below.
/
BLOWER FAN
\
\,u
EXPANSION VALVE(Meters the requiredamount of refrigerantinto the evaporator)
A/C PRESSURE SWITCHWhen the refriqerant is below196 kPa (2.0 kgi/cm',28 psi)or above 3,140 kPa (32 kgf/cm'455 psi), the Py'c pressureswitch opens the circuit tothe Py'C switch and stops theair conditioning to protect thecompressor-
RECEIVER/DRYER(Traps debris, andremoves morsturel
APOBATOR TEMPERATURESENSOR
THERMAL PROTECTOR(Opens the compressor clutch circuitwhen the compressot temperaturebecomes too high)
RELIEF VALVE(Relieves pressure at the compressorwhen the pressure is too high)
A/C COMPRESSOR(Suction and comoression)\-^
I HrcH PRESSURE vAPoR
[ '.... -:--l Low PREsSUBE LrourD
tffi Low PREssURE vAPoR
This vehicle uses HFC-134a (R-'134a) refrigerant which does not contain ch lorofluorocarbons. Pay attention to the
following service items:
. Do not mix refrigerants CFC-12 (R-12) and HFC-134a (R-134a). They are notcompatible.. Use onlythe recommended polyalkyleneglycol (PAG ) refrigera nt oil (KElHlN SP '!0) designedfortheR-134a
compressor. Intermixing the recommended (PAG) refrigerant oil with any other retrigerant oil will result in
compressor failu re.. AllAy'C system parts (compressor, discharge line, suction line, evaporator, condenser, receiver/dryer. expansion
valve, O-rings for joints) have to be designed for refrigerant R 134a. Do not exchange with R-'12 parts.
. Use a halogen gas leak detector designed for refrigerant R-134a.. R-12 and R-134a refrigerant servicing equipment are not interchangeable. Use only a recovery/recycling/charging
station that is U.L.-listed and is certified to meet the requirements of SAE J2210 to service R-134a air conditioning
system.. Always recover the refrigerant R-134a with an approved recovery/recycling/charging station before disconnecting
any Ay'C fifting.
/-
CONDENSER(Radiation of heat)
21-12

Heating and Air Conditioning
DTC Troubleshooting
DTC 7: An Open in the Air Mix Control Motor
Circuit
1. Test the air mix control motor {see page 2'l-341.
ls the air mix control motor OK?
YES-Go to step 2.
NO-Replace the air mix control motor.l
2. Disconnect the air mix control motor 5P connector.
3. Disconnect heater control panel connectors A {14P)
and B (22P).
4. Check for continuity between the following
terminals of heater control panel connectors A
(14P) and B (22P) and the air mix control motor 5P
connector,
14P: 5P:
No. 1 No.5
No.2 No.4
No.3 No.2
No.9 No. 1
22P: 5P:
No.6 No.3
Wire side ol lem.letehi.6ls
ls there continuity?
YES-Check for loose wires or poor connections at
heater control oanel connectors A (14P) and B (22P)
and at the air mix control motor 5P connector. lf the
connections are good. substitute a known-good air
mix control motor, and recheck, lf the symptom/
indication goes away, replace the original air mix
control motor. lf the symptom/indication continues,
substitute a known-good heater control panel, and
recheck. lf the symptom/indication goes away,
replace the original heater control panel.l
NO Repair any open inthewire(s) ketweenthe
heater control panel and the air mix control
motor.l
21-16
DTC 8: A Short in the Air Mix Control Motor
Circuit
1. Test the air mix control motor(see page 21-341.
ls the ait mix control motor OK?
YES-Go to step 2.
NO-Replace the air mix contorol motor.I
2. Disconnect the air mix control motor 5P connector.
3. Disconnect heater control panel connectors A (14P)
and B (22P).
4. Check for continuity between body ground and
heater control panel connector A (14P) terminals
No. 1, 2, 3, and 9 individually, and between body
ground and heater control panel connector B (22P)
terminal No. 6.
HEATERCONTROL PANEL CONNECTOR A {I4PI
HEATER CONTFOL PANELCONNECTOR B I22P1
ls therc continuity?
YES-Repair any shortto body ground ln the
wire(s) between the heater control panel and the air
mix control motor.l
NO-Go to step 5.
Wire side of female terminals
Wire side oilema e lerminals