2002 HONDA CIVIC Workshop Manual

EPS Components
DTC Troubleshooting Index
DTCDetection ltemNote
DTC; 12A problem with voltage for torque sensor T/SlG(see page 17-28)
DTC: 16A problem with average of voltage for torque sensor VT3 and VT6(see page 17-29)
DTC: 17A problem with the voltage for torque sensor 12 V power source Vcc 1(see page 17-31)
DTC: 18A problem with the voltage for torque sensor 5 V power source Vcc 2(see page 17-31)
DfC:22A problem with the average for vehicle speed and engine speed(see page 17-33)
Excessive change of the vehicle speed sensor signal{see page 17-33)
DTC: 23A problem with the engine speed signal circuit(see page 17-33)
DTC: 37A problem with the circuit for input motor voltage in the EPS control unit(see page 17-35)
DTC: 41A problem with the motor voltage(see page 17 36)
DfC: 42A problem with the motor driven current (open circuit or short to grounol(see page '17-38)
DTC: 43A problem with the motor driven current (short to power)(see page 17-41)
DTC: 45A problem with the motor driven current (open circuit or short to grou nol(see page 17-38)
DfC: 47A problem with the motor relav in the EPS control unit{see page 17-42)
DTC: 50A problem with the CPU in the EPS control unit(see page 17-43)
DTC: 51A problem with EEPROM in the EPS control unlt(see page 17-43)
DTC: 62Fail-safe relay stuck ON(see page 17-44)
DTC: 64A problem with low battery voltage
Fail-safe relay contact failure
(see page 17-44)
(see page 17-44)
DTC: 66A problem with the motor driven voltage{see page 17 45)
DTC: 67A problem with the torque sensor l/F circuit(see page 17'45)
DTC: 68A problem with the interlock circuit (torque){see page 17-45)
DTC: 69A problem with the interlock circuit (current)(see page 17-46)
17-22

Symptom Troubleshooting Index
SymptomDiagnostic procedureAlso check fo]
EPS indicator does not
come on
EPS lndicator Circuit Troubleshooting (see page 17-47)
EPS indicator does not go
off and no DTC is stored
EPS Indicator Circuit Troubleshooting (see page 17-47)
EPS indicator does not stay
on, no DTC is stored, and
there is no power assist
1. Check the motor wires between the EPS control unit and the
motor for a short to ground. Repair as needed.
2. lf the motor wires are OK, replace the steering gearbox
{short in the motor).
17-23

EPS Gomponents
System Description
EPS Gontrol Unit Inputs and Outputs at Connector A (2pl
EPS CONTROL UNIT CONNECTOR A {2P)
Wire side of female terminals
EPS Control Unit Inputs and Outputs at Connector B (2P)
EPS CONTROL UNIT CONNECTOB B {2P}
Wire side of female terminals
TermanalnumbolWire colorTerminal sign(Terminal namelDescriptionMeasurementTerminalsConditionslqnitiqr switch ON (lllVoltage
WHT/BLU-' BAT(Plus bafterv)Power source for theactuator motorl GroundConstantBattery voltage
28LKPGGround forthe actuator2-Ground
TerminalnumDerWire cololTerminalsign{Te.mioalname)DescriptionMeasuremenlTerminalsConditionslqnition switch ON llllVoltage
1REDM1(Motor 1Drives lhe actuator motor1-Ground
2GRNM2Drives the actuator motor2'Ground
17-24

EPS Gontrol Unit Inputs and Outputs at Connestor C (20P1
EPS CONTROL UNIT CONNECTOR C (2OP)
Wire side of female terminals
TerminalnumbelWire colorTerminal sign{Terminel name}DescriplionMeasuremeniTerminalsConditions{lqnition switch ON {lll)Voltage
2PNKT/S GND(Torque sensor qround)Ground for the torque
ORNvccl(Voltaqe common 1Power source fortorque3-Groundtartthe enqrneBa$erv voltaqeOV
5YEUBEDVT6(Voltaqe torque 6)Detects torque sensorstonal5 GroundStartthe engine andturn the steerino wheelAbout
YEUBLU(Warninq lamp)Drives the EPS indicatorlidhr6 GroundEPS ONtnotcatol uTl-OVBanerv voltaqe
7BLUAVHTVSP(Vehicle speed pulseiDetects the vehicle speedinput signal for the speedsensor or the ECM (4 pulse/
Raise the vehicle off theground and spin theAlternatingvoltage aboutOV 5V OV-5V
BRNSCS{Servjco check siqnal)Detects service check8-GroundSCS not groundedBattery voltage
10YELIG1llqnition 1Power source for activating10-Groundon switch ON (ll)Batterv voltaqeon switch OFF11G RN//ELvcc2(Voltaqe common 2)Drives the torque sensor1'l-Groundtan the enoineAbout5Von switch OFF8LU/ORNVT3(Voltaoe toroue 3)Detects torque sensor13-GroundStartthe engine andtrrrn the steerino wheelAbout5-0 v
YEUBLKT/SIG(Torque sensor F/SDetects torque sensorsrgnal15-GroundStartthe engineMomentarily 5 V
1'lLT GRN/BI KPSWiPower steerino switch)Provides power steeringswitch sionall7-GroundStartthe engine andnrrn the steerino wheel0-12V
19BLUNEPDetects the engine pulse19-GroundStartthe engine, and let;t idte
20GRYDIAG-HCommunications withHonda PGNI Tester20-GroundPGM Tester not5V
17-25

a
EPS Components
\Circuit Diagram
\
SPE€DSENSOR3P CONNECTOR
@
TOFOUE SENSOR6P CONNECTOR
lli2l3Fr;T;T-I(=J_:_LvJ
Wn. !ide ot f.m.l€ r.fmin.ls
GAUGE ASSEMBLY 22P CONNECTON
GAUGE ASSEMATY 22P CONNECTOR
17-26

EPS COI{IFOI UNITcou{EcToR A (2P)
F-l
A
EPS CONTNOL UNITco|lNEcTofi 8 {2P}
|ll
t2)
Wir. !.le ol l.m.l. t.tman.r.
MOTOFCONNECTOR
riTt
OATA !IN( CONN€CTOA (T6P)
vTTrvaEvnrv
wwzna
T.rmin.l.id. oll.m.l.r.rmin.l.
17-27

EPS Components
DTC Troubleshooting
DTC 12: Torque Sensor T/SIG
1. Clear the DTC.
2. Stan the engine.
3. Wait at least 10 seconds.
Does the EPS indicatot come on?
YES Go to step 4.
NO Check for loose wires or poor connections. lf
the connections are good, the system is OK at this
time.l
4.Stop the engine, and verify the DTC.
ls DTC12 indicated?
YES Go to slep 5.
NO-Perform the appropriate troubleshooting for
the code indicated. t
Make sure the ignition switch is OFF, then
disconnect EPS control unit connector C (20P) and
the torque sensor 6P connector.
Check for continuity between EPS control unit
connector C (20P)terminal No. 15 and body ground.
EPS CONTROL UNIT CONNECTOR C {2OP)
Wire side of female terminals
ls there continuity?
YES- Repair short to body ground in the wire
between the torque sensor and EPS control unit.l
NO Go to step 7.
5.
17-28
1.
8.
Turn the ignition switch ON (ll).
Measure the voltage between EPS control unit
connector C (20P)terminal No. 15 and body ground.
EPS CONTROL UNIT CONNECTOR C (2OP)
2356180
T/SIG{YEL/BLK)
Wire side ot lemale terminals
I s there battery v oltage?
YES-Repair short to power in the + circuit wire
between the torque sensor and EPS control unit.l
NO Go to step 9.
Turn the ignition switch OFF.
Check for continuity between EPS control unit
connector C (20P) terminal No. 15 and the torque
sensor 6P connector terminal No. 4.
EPS CONTROL UNIT CONNECTOR C (2OPI
\9.
10.
T/SIG(YEL/BLK)Wire side of female terminals
TOROUE SENSOR6P CONNECTOR
T/SIG(YEL/BLK)
ls there continuity?
YES Go to step 1'1,
NO Repair open in the wire between the torque
sensor and the EPS control unit.I
Wire side ot female terminals

'I 1.Substitute a known-good EPS control unit, and
connect the all disconnected connectors.
Sta rt the engine.
Does the EPS indicator come on?
YES Go to step 13.
NO Check for loose EPS control unitconnectors. lf
necessary, replace the EPS control unit and
retest.l
Stop the engine, and verify the DTC.
ls DTCl2 indicated?
YES Check for loose torque sensor connectors.
lf necessary, substitute a known-good steering
gearbox and recheck.l
NO-Perform the appropriate troubleshooting for
the code indicated. !
12.
13.
DTC 16: Torque Sensor VT3 and W6
1. Clear the DTC.
2. Start the engine.
3. Wait at least 10 seconds.
Does the EPS indicator come on?
YES Go to step 4.
NO Check for loose wires or poor connnections. lf
the connections are good, the system is OK at this
time.l
4. Stop the engine, and verify the DTC.
ls DTC16 indicated?
YES-Go to step 5.
NO Perform the appropriate troubleshooting for
the code indicated. t
5. Make sure the ignition switch is OFF, then
disconnect EPS control unit connector C (20P) and
the torque sensor 6P connector.
6, Check for continuity between the appropriate EPS
control unit connector C (20P) terminal and body
ground (see table).
Terminal nameEPS control unit connector C
terminal No.
Vccl3
Vcc211
VT313
VT65
T/S GND2
W re s d€ oltemalelermi.als
ls there continuity?
YES- Repair short to body ground in the
appropriate sensor circuit between the torque
sensor and EPS control unit, !
NO Go to step 7.
{cont'd)
EPS CONINOT UNITCONNECIOR C (2OP)
17-29