Nissan Altima L32. Instruction — part 1396
EPS SYSTEM
STC-3
< FUNCTION DIAGNOSIS >
C
D
E
F
H
I
J
K
L
M
A
B
STC
N
O
P
FUNCTION DIAGNOSIS
EPS SYSTEM
System Diagram
INFOID:0000000004205824
CONTROL DIAGRAM
System Description
INFOID:0000000004205825
• The EPS system controls the power steering solenoid valve through the power steering control unit.
• 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.
JSGIA0119GB
JSGIA0141GB
JSGIA0020GB
STC-4
< FUNCTION DIAGNOSIS >
EPS SYSTEM
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.
Component Parts Location
INFOID:0000000004205826
JSGIA0021GB
ALGIA0029ZZ
EPS SYSTEM
STC-5
< FUNCTION DIAGNOSIS >
C
D
E
F
H
I
J
K
L
M
A
B
STC
N
O
P
Component Description
INFOID:0000000004205827
1.
Power steering control unit M59
(view with glove box removed)
2.
Power steering solenoid valve E14
Component parts
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 meter
Refer to
.
ECM
Refer to
.
Power steering solenoid valve
Refer to
.
STC-6
< COMPONENT DIAGNOSIS >
POWER SUPPLY AND GROUND CIRCUIT
COMPONENT DIAGNOSIS
POWER SUPPLY AND GROUND CIRCUIT
Description
INFOID:0000000004205828
• EPS system functions by ignition power supply.
Diagnosis Procedure
INFOID:0000000004205829
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 con-
nector M59 terminal 3 and ground.
4. Turn the ignition switch ON.
CAUTION:
Never start the engine.
5. Check voltage between power steering control unit harness con-
nector M59 terminal 3 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.
2.
CHECK GROUND CIRCUIT
1. Turn the ignition switch OFF.
2. Check continuity between power steering control unit harness
connector M59 terminal 6 and ground.
Is the inspection result normal?
YES
>> GO TO 3.
NO
>> Repair open circuit or short to power in harness or con-
nectors.
3.
CHECK TERMINALS AND HARNESS CONNECTORS
Check power steering control unit pin terminals for damage or loose connection with harness connector.
Power steering control unit
Voltage (Approx.)
Connector
Terminal
M59
3 - Ground
0 V
AWGIA0032ZZ
Power steering control unit
Voltage (Approx.)
Connector
Terminal
M59
3 - Ground
Battery voltage
AWGIA0033ZZ
Power steering control unit
Continuity
Connector
Terminal
M59
6 - Ground
Existed
AWGIA0034ZZ
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