NISSAN TEANA 2008 Service Manual

EPS SYSTEM
STC-3
< FUNCTION DIAGNOSIS >
C
D
E
F
H
I
J
K
L
MA
B
STC
N
O
P
FUNCTION DIAGNOSIS
EPS SYSTEM
System DiagramINFOID:0000000003893522
CONTROL DIAGRAM
CROSS-SECTIONAL VIEW
System DescriptionINFOID:0000000003893523
• The EPS system controls the power steering solenoid valve through the power steering control unit.
JSGIA0119GB
1. Combination meter 2. Power steering control unit 3. Power steering solenoid valve
4. Steering gear assembly 5. Gear housing assembly 6. Gear sub-assembly
7. Pinion 8. Power steering oil pump 9. Reservoir tank
JSGIA0376ZZ

STC-4
< FUNCTION DIAGNOSIS >
EPS SYSTEM
 The valve driving voltage to control the power steering solenoid
valve varies according to the vehicle speed.
OPERATION PRINCIPLE
During Parking (When Turning The Steering Wheel To The Right.)
1. Power steering solenoid valve is closed while a vehicle is stopped.
2. Pinion “1R”, “2R” and “3R” are closed depending on steering torque of steering wheel.
3. Oil pressure “P” in the gear housing assembly is the sum of oil pressures occurred in “2R” and “3R”. This
results in a light steering force because of high pressure.
During High-speed Operation
1. Power steering solenoid valve is opened during high-speed operation.
2. Pinion “1R”, “2R” and “3R” are closed depending on steering torque of steering wheel.
3. Oil pressure “2R” does not occur because the power steering solenoid valve is on full throttle.
4. Oil pressure “P” in the gear housing assembly includes only oil pressure occurred in “3R” and results in a
heavy steering force.
JSGIA0374GB
JSGIA0020GB
JSGIA0021GB

EPS SYSTEM
STC-5
< FUNCTION DIAGNOSIS >
C
D
E
F
H
I
J
K
L
MA
B
STC
N
O
P
Component Parts LocationINFOID:0000000003893524
Component DescriptionINFOID:0000000003893525
1. Power steering solenoid valve 2. Power steering control unit
A. Steering gear assembly B. Glove box assembly removed
: Vehicle front
JSGIA0406ZZ
Component parts Reference/Function
Power steering control unit Signals from various sensors control the driving voltage to the power steering solenoid valve.
 The power steering control unit controls the driving voltage to the power steering solenoid valve
for maintaining the power steering assist force when the fail-safe function is activated. (The en-
gine speed signals control EPS system if any vehicle speed signal error is detected.)
Combination meterSTC-11, "
Description"
ECMSTC-9, "Description"
Power steering solenoid valveSTC-7, "Description"

STC-6
< COMPONENT DIAGNOSIS >
POWER SUPPLY AND GROUND CIRCUIT
COMPONENT DIAGNOSIS
POWER SUPPLY AND GROUND CIRCUIT
DescriptionINFOID:0000000003893526
Power supply to EPS system
Diagnosis ProcedureINFOID:0000000003893527
1.CHECK POWER SUPPLY
1. Turn the ignition switch OFF.
2. Disconnect power steering control unit harness connector.
3. Check voltage between power steering control unit harness connector and ground.
4. Turn the ignition switch ON.
CAUTION:
Never start the engine.
5. Check voltage between power steering control unit harness connector and ground.
Is the inspection result normal?
YES >> GO TO 2.
NO >> Check the following. If any items are damaged, repair or replace damaged parts.
 10A fuses (#3) open
- Harness for short or open between ignition switch and power steering control unit harness con-
nector No. 3 terminal.
- Ignition switch. Refer to PCS-64, "
Component Inspection".
2.CHECK GROUND CIRCUIT
1. Turn the ignition switch OFF.
2. Check continuity between power steering control unit harness connector and ground.
Is the inspection result normal?
YES >> GO TO 3.
NO >> Repair open circuit or short to power in harness or connectors.
3.CHECK TERMINALS AND HARNESS CONNECTORS
Check power steering control unit pin terminals for damage or loose connection with harness connector.
Is the inspection result normal?
YES >> INSPECTION END
NO >> Repair or replace damaged parts.
Power steering control unit
—Voltage
Connector Terminal
M61 3 Ground 0 V
Power steering control unit
— Voltage
Connector Terminal
M61 3 Ground Battery voltage
Power steering control unit
—Continuity
Connector Terminal
M61 6 Ground Existed

POWER STEERING SOLENOID VALVE
STC-7
< COMPONENT DIAGNOSIS >
C
D
E
F
H
I
J
K
L
MA
B
STC
N
O
P
POWER STEERING SOLENOID VALVE
DescriptionINFOID:0000000003893528
Power steering solenoid valve controls the power steering oil pressure in the gear housing assembly.
Diagnosis ProcedureINFOID:0000000003893529
1.CHECK POWER STEERING SOLENOID VALVE SIGNAL
1. Turn the ignition switch OFF.
2. Check voltage between power steering control unit harness connector and ground.
Is the inspection result normal?
YES >> GO TO 2.
NO >> GO TO 4.
2.CHECK HARNESS BETWEEN POWER STEERING SOLENOID VALVE AND POWER STEERING CON-
TROL UNIT
1. Turn the ignition switch OFF.
2. Disconnect power steering solenoid valve harness connector.
3. Disconnect power steering control unit harness connector.
4. Check the continuity between power steering solenoid valve harness connector and the power steering
control unit harness connector.
5. Check continuity between power steering control unit harness connector and ground.
Is the inspection result normal?
YES >> GO TO 3.
NO >> Repair or replace damaged parts.
3.CHECK POWER STEERING SOLENOID VALVE
Check power steering solenoid valve. Refer to STC-8, "
Component Inspection".
Is the inspection result normal?
YES >> GO TO 4.
NO >> Replace gear-sub assembly. Refer to ST-18, "
Exploded View".
4.CHECK TERMINALS AND HARNESS CONNECTORS
 Check power steering control unit pin terminals for damage or loose connection with harness connector.
 Check power steering solenoid valve pin terminals for damage or loose connection with harness connector.
Is the inspection result normal?
Power steering control unit
— Condition Voltage (Approx.)
Connector Terminal
M61 1 GroundVehicle speed: 0 km/h (0 MPH)
(Engine is running)4.4 – 6.6 V
Vehicle speed: 100 km/h (62 MPH) 2.4 – 3.6 V
Power steering solenoid valve Power steering control unit
Continuity
Connector Terminal Connector Terminal
E52 1 M61 1 Existed
E52 2 M61 5 Existed
Power steering control unit
—Continuity
Connector Terminal
M61 1
Ground Not existed
M61 5

STC-8
< COMPONENT DIAGNOSIS >
POWER STEERING SOLENOID VALVE
YES >> INSPECTION END
NO >> Repair or replace damaged parts.
Component InspectionINFOID:0000000003893530
1.CHECK POWER STEERING SOLENOID VALVE
1. Turn the ignition switch OFF.
2. Disconnect power steering solenoid valve harness connector.
3. Check resistance between power steering solenoid valve connector terminals.
4. Check power steering solenoid valve by listening for its operation sound while applying battery voltage to
power steering solenoid valve connector E52 terminals 1 (positive) and 2 (negative).
Is the inspection result normal?
YES >> INSPECTION END
NO >> Replace gear-sub assembly. Refer to ST-18, "
Exploded View".
Power steering solenoid valve
Resistance (Approx.)
Connector Terminal
E52 1 2 4 – 6 Ω

ENGINE SPEED SIGNAL CIRCUIT
STC-9
< COMPONENT DIAGNOSIS >
C
D
E
F
H
I
J
K
L
MA
B
STC
N
O
P
ENGINE SPEED SIGNAL CIRCUIT
DescriptionINFOID:0000000003893531
ECM sends engine speed signal to power steering control unit.
Diagnosis ProcedureINFOID:0000000003893532
1.PERFORM ECM SELF-DIAGNOSIS
With CONSULT-III
1. Turn the ignition switch ON.
Perform ECM self-diagnosis. Refer to EC-113, "
CONSULT-III Function".
Is any DTC detected?
YES >> Check the DTC.
NO >> GO TO 2.
2.CHECK HARNESS BETWEEN ECM AND POWER STEERING CONTROL UNIT
1. Turn the ignition switch OFF.
2. Disconnect ECM harness connectors.
3. Disconnect power steering control unit harness connector.
4. Check continuity between ECM harness connector and power steering control unit harness connector.
5. Check continuity between power steering control unit harness connector and ground.
Is the inspection result normal?
YES >> GO TO 3.
NO >> Repair or replace damaged parts.
3.CHECK ENGINE SPEED SIGNAL (1)
1. Connect ECM harness connectors.
2. Check signal between ECM harness connector and ground with oscilloscope.
ECM Power steering control unit
Continuity
Connector Terminal Connector Terminal
E16 94 M61 10 Existed
Power steering control unit
— Continuity
Connector Terminal
M61 10 Ground Not existed

STC-10
< COMPONENT DIAGNOSIS >
ENGINE SPEED SIGNAL CIRCUIT
Is the inspection result normal?
YES >> GO TO 4.
NO >> Replace ECM. Refer to EC-14, "
ADDITIONAL SERVICE WHEN REPLACING CONTROL UNIT :
Description".
4.CHECK ENGINE SPEED SIGNAL (2)
1. Connect power steering control unit harness connector.
2. Check signal between power steering control unit harness connector and ground with oscilloscope.
Is the inspection result normal?
YES >> GO TO 5.
NO >> Replace power steering control unit. Refer to STC-19, "
Exploded View".
5.CHECK TERMINALS AND HARNESS CONNECTORS
 Check power steering control unit pin terminals for damage or loose connection with harness connector.
 Check ECM pin terminals for damage or loose connection with harness connector.
Is the inspection result normal?
YES >> INSPECTION END
NO >> Repair or replace damaged parts.
ECM
— Condition Voltage (Approx.)
Connector Terminal
E16 94 GroundEngine is running
 Warm-up condition
 Idle speed
Engine is running
 Warm-up condition
 Engine speed: Approx. 2,000 rpm
JSGIA0143ZZ
PBIA3655J
Power steering control unit
— Condition Voltage (Approx.)
Connector Terminal
M61 10 GroundEngine is running
 Warm-up condition
 Idle speed
Engine is running
 Warm-up condition
 Engine speed: Approx. 2,000 rpm
JSGIA0143ZZ
PBIA3655J

VEHICLE SPEED SIGNAL CIRCUIT
STC-11
< COMPONENT DIAGNOSIS >
C
D
E
F
H
I
J
K
L
MA
B
STC
N
O
P
VEHICLE SPEED SIGNAL CIRCUIT
DescriptionINFOID:0000000003893533
Combination meter sends vehicle speed signal to power steering control unit.
Diagnosis ProcedureINFOID:0000000003893534
1.PERFORM COMBINATION METER SELF-DIAGNOSIS
With CONSULT-III
1. Turn the ignition switch ON.
2. Perform combination meter self-diagnosis. Refer to MWI-33, "
CONSULT-III Function (METER/M&A)".
Is any DTC detected?
YES >> Check the DTC.
NO >> GO TO 2.
2.CHECK HARNESS BETWEEN COMBINATION METER AND POWER STEERING CONTROL UNIT
1. Turn the ignition switch OFF.
2. Disconnect combination meter harness connector.
3. Disconnect power steering control unit harness connector.
4. Check continuity between combination meter harness connector and power steering control unit harness
connector.
5. Check continuity between power steering control unit harness connector and ground.
Is the inspection result normal?
YES >> GO TO 3.
NO >> Repair or replace damaged parts.
3.CHECK VEHICLE SPEED SIGNAL (1)
1. Connect combination meter harness connector.
2. Check combination meter input/output standard values. Refer to MWI-53, "
Reference Value".
Is the inspection result normal?
YES >> GO TO 4.
NO >> Replace combination meter Refer to MWI-126, "
Exploded View".
4.CHECK VEHICLE SPEED SIGNAL (2)
1. Connect power steering control unit harness connector.
2. Check signal between power steering control unit harness connector and ground with oscilloscope.
Combination meter Power steering control unit
Continuity
Connector Terminal Connector Terminal
M3430M618Existed
Power steering control unit
—Continuity
Connector Terminal
M61 8 Ground Not existed

STC-12
< COMPONENT DIAGNOSIS >
VEHICLE SPEED SIGNAL CIRCUIT
Is the inspection result normal?
YES >> GO TO 5.
NO >> Replace power steering control unit. Refer to STC-19, "
Exploded View".
5.CHECK TERMINALS AND HARNESS CONNECTORS
 Check power steering control unit pin terminals for damage or loose connection with harness connector.
 Check combination meter pin terminals for damage or loose connection with harness connector.
Is the inspection result normal?
YES >> INSPECTION END
NO >> Repair or replace damaged parts.
Power steering control unit
— Condition Voltage (Approx.)
Connector Terminal
M61 8 GroundVehicle speed: 40 km/h (25 MPH)
CAUTION:
Check air pressure of tire under
standard condition.
JSNIA0015GB