2003 HONDA CIVIC Circuit

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

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 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

EPS Components
I
7.
8.
DTC Troubleshooting (cont'd)
Turn the ignition switch ON (ll).
Measure the voltage between the appropriate EPS
control unit connector C (20P) terminal and bodyground (see table).
Terminal nameEPS control unit connector C
terminal No.
Vccl3
Vcc211
VT313
VT65
T/S GND2
ls thete battery voltage?
YES Repair shon to power in the + circuit wire
between the EPS control unit and torque sensor.l
NO Go to step 9.
EPS CONTROL UNIT CONNECTOR C {2OP}
Wire side of female terminals
17-30
9.
10.
Turn the ignition switch OFF.
Check for continuity between the appropriate EPS
control unit connector C {20P) terminal and the
torque sensor terminal (see table).
TOROUE SENSOR 6P CONNECTOR
Vccz(GRN/YELI
Wire side offemale terminals
VT6 {YEL/RED)
EPS CONTROL UNITCONNECTOR C I2OP)
VT6 {YEL/RED}
\
Wire side of female terminals
ls there continuty?
YES Go to step 11.
NO Repair open in the appropriate torque sensor
wire circuit between the EPS control unit and the
torque sensor.l
\
Terminal
name
Torque Sensor
terminal No,
EPS control
unit connector
C terminal No.
Vccl23
Vcc2311
VT3'l't3
VT665
T/S GND62
T/S GND {PNK)

'14. Check for continultv between EPS control unit
connector C (20P)terminal No. 19 and ECM
connector E (31P) terminal No. 26.
ECM CONNECTOR E {31PI
ls thete continuity?
YES-Go to step 15.
NO-Repair open in the wire between the EPS
control unit and ECM.I
Disconnect the gauge assembly 22P connector.
Check for continuity between EPS control unit
connector C (20P)terminal No. 19 and body ground,
EPS CONTROL UNIT CONNECTOR C (2OP}
Wire side of female terminals
ls there continuity?
YES Repair shortto body ground in the wire
between the EPS control unit, the test tachometer
connector, the gauge assembly, and the ECM.I
NO Check for loose ECM control unit connectors.
lf necessary, substitute a known-good ECM control
unit and recheck.I
15.
DTC 37: EPS Control Unit Internal Circuit(lnput Circuit For Motor Voltage)
1. Clear the DTC.
2. Start the engine.
3. Turn the steering wheel from lock-to-lock several
times, and wait 10 seconds or more.
Does the EPS indicator 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
trme.l
4. Stop the engine, and verify the DTC.
ls DTC 37 indicated?
Y€S Check for loose EPS control unit conneclors.
lf necessary, substitute a known-good EPS control
unit and recheck.l
NO Perform the appropriate troubleshooting for
the code indicated.l
17-35

EPS Components
DTC Troubleshooting (cont'dl
DTC 41: Voltage For Motor
1. Clear the DTC.
2. Start the engine.
3. Turn the steering wheel from lock-to-lock several
times, and wait 10 seconds or more,
Does the EPS indicator 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 DTC 41 indicated?
YES Go to step 5.
NO Perform the appropriate troubleshooting for
the code indicated.l
5. Make sure the ignition switch is OFF, then
disconnect EPS control unit connector B (2P) and
the motor 2P conneclor.
6. Check for continuity between EPS control unit
connector B (2P) terminal No. 1 and body ground.
EPS CONTROL UNIT CONNECTOR B {2P}
M1 (RED} HF---t||
Itr(f))
T,L
Wire side of female terminals
ls there continuity?
YES Repair short to body ground in the RED wire
between the EPS control unit and the motor. !
NO-Go to step 7.
17-36
7. Check for continuity between EPS control unit
connector B (2P)terminal No. 2 and body ground.
EPS CONTROL UNIT CONNECTOR B I2P)
TitM2 {GRN) FJ
-r
o)
TI
Wire side of female terminals
ls there continuity?
YES-Repair short to body ground in the GRN wire
between the EPS control unit and the motor,l
NO Go to step 8.
Check for continuity between EPS control unit
connector B (2P)terminal No. 1 and No. 2.
EPS CONTROL UNIT CONNECTOR B {2P)
Wire side of female terminals
ls there continuity?
YES Repair short between the RED and GRN
wires in the motor circuit between the EPS control
unit and the motor.l
NO Go to step 9.
M2 (GRNI
.l
\

9. Turn the ignition switch ON (ll), and measure the
voltage between EPS control unit connector B (2P)
terminal No. 1 and body ground
EPS CONTROL UNIT CONNECTOR B (2P)
M1 IREDI Hr-_ -1 ||
tr,<.)\uL,/Y
I
Wire side oI female terminals
Is there battety voltage?
YES Repair short to power in the + circuit wire
between the EPS control unit and the motor.I
NO-Go to step 10.
Measure the voltage between EPS control unit
connector B (2P)terminal No.2 and body ground.
EPS CONTROL UNIT CONNECTOR B (2P)
10.
raz rcnrrrr l{l-t . I
I(v)
YI
Wire side of female terminals
ls there battery voltage?
YES-Repair shortto power in the - circuitwire
between the EPS control unit and the motor.!
NO Go to step 11.
11.Turn the ignition switch is OFF.
Substitute a known-good EPS control unit, and
connect all the disconnected connectors.
Start the engine, and turn the steering wheel from
lock to lock several times.
Does the EPS indicator come on?
YES-Go to step 14.
NO-Check for loose or poor connections atthe
EPS control unit and the motor connections. lfthe
connections are good, replace the EPS control unit
and recheck.l
Stop the engine, and verity the DTC.
ls DTC 41 ind icated?
YES Replace the steering gearbox motor and
recheck.l
NO Perform the appropriate troubleshooting for
the code indicated.l
13.
14.
17-37