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STC-4
< SYSTEM DESCRIPTION >
COMPONENT PARTS
SYSTEM DESCRIPTION
COMPONENT PARTS
Component Parts LocationINFOID:0000000006256115
Component DescriptionINFOID:0000000006256116
Power Steering Control UnitINFOID:0000000006256117
Signals from various sensors control the driving voltage to the power steering solenoid valve.
The power steering control unit controls the driving vo ltage to the power steering solenoid valve for maintain-
ing the power steering assist force when the fail-safe function is activated. (The engine speed signals control
EPS system if any vehicle s peed signal error is detected.)
Power Steering Solenoid ValveINFOID:0000000006256118
Power steering solenoid valve controls the power steering oil pressure in the gear housing assembly.
1. ECM
Refer to EC-16, "
Component Parts
Location". 2. Combination meter
Refer to MWI-6, "
METER SYSTEM :
Component Parts Location". 3. Power steering control unit
4. Power steering solenoid valve
A. Glove box assembly removed B. Steering gear assembly
JPGIB0006ZZ
Component parts Reference/Function
Power steering control unit STC-4, "
Power Steering Control Unit"
Power steering solenoid valveSTC-4, "Power Steering Solenoid Valve"
Combination meter Transmits vehicle speed signal to power steering control unit.
ECM Transmits engine speed signal to power steering control unit.
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SYSTEMSTC-5
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SYSTEM
EPS SYSTEM
EPS SYSTEM : System DescriptionINFOID:0000000006256119
The EPS system controls the power steering sol enoid valve through the power steering control unit.
The valve driving voltage to control the power steering solenoid
valve varies according to the vehicle speed.
CONTROL DIAGRAM
CROSS-SECTIONAL VIEW
JPGIB0021GB
JPGIB0017GB
SGIA1389E
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STC-6
< SYSTEM DESCRIPTION >
SYSTEM
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”. Thisresults 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 pow er 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.
EPS SYSTEM : Fail-Safe INFOID:0000000006256120
EPS system
EPS system enters the fail-safe mode (that allows the steering
force to be controlled without impairi ng the drivability) if any of the
input/output values to/from EPS system (power steering control
unit) deviate from the standard range.
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 engine
speed signals control EPS system if any vehicle speed signal error
is detected.)
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
JSGIA0020GB
JSGIA0021GB
JPGIB0022GB
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SYSTEMSTC-7
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Error area and root cause Cancel condition
Engine speed is 1,500 rpm or more and there is no vehicle speed signal input for
over 10 seconds during vehicle travel. When a vehicle speed signal of 2 km/h (1.2
MPH) or more is inputted.
Ignition switch is turned OFF to ON.
Vehicle speed signal has abruptly dropped from 30 km/h (19 MPH) or more to 2
km/h (1.2 MPH) or less within 1.4 seconds.
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STC-8
< ECU DIAGNOSIS INFORMATION >
POWER STEERING CONTROL UNIT
ECU DIAGNOSIS INFORMATION
POWER STEERING CONTROL UNIT
Reference Value INFOID:0000000006256121
TERMINAL LAYOUT
PHYSICAL VALUES
JSGIA0023ZZ
Te r m i n a l N o .(Wire color) Description
Condition Value (Approx.)
+ - Signal name Input/
Output
1
(R) GroundPower steering
solenoid
valve control voltage OutputVehicle 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
3
(GR) GroundIgnition switch power
supply InputIgnition switch: ON Battery voltage
Ignition switch: OFF 0 V
5
(L) Ground
Power steering
solenoid
valve ground —Always 0 V
6
(B) Ground Ground — Always 0 V
8
(SB) Ground Vehicle speed signal Input Vehicle speed: 40 km/h (25 MPH)
CAUTION:
Check air pressure of tire under
standard condition.NOTE:
The maximum voltage varies de-
pending on the specification
(destination unit).
JSNIA0015GB
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POWER STEERING CONTROL UNITSTC-9
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When using circuit tester or osci lloscope to measure voltage for in spection, be sure not to forcibly
extend any connector terminals.
Fail-Safe INFOID:0000000006256122
EPS system
EPS system enters the fail-safe mode (that allows the steering
force to be controlled without impair ing the drivability) if any of the
input/output values to/from EPS system (power steering control
unit) deviate from the standard range.
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 engine
speed signals control EPS system if any vehicle speed signal error
is detected.)
10
(B/SB) Ground Engine speed signal Input Engine is running
Warm-up condition
Idle speed
Engine is running
Warm-up condition
Engine speed: Approx. 2,000
rpm
Te r m i n a l N o .
(Wire color) Description
Condition Value (Approx.)
+ - Signal name Input/
OutputJPBIA3352ZZ
JPBIA3354ZZ
JPGIB0022GB
Error area and root cause Cancel condition
Engine speed is 1,500 rpm or more and there is no vehicle speed signal input for
over 10 seconds during vehicle travel. When a vehicle speed signal of 2 km/h (1.2
MPH) or more is inputted.
Ignition switch is turned OFF to ON.
Vehicle speed signal has abruptly dropped from 30 km/h (19 MPH) or more to 2
km/h (1.2 MPH) or less within 1.4 seconds.
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STC-10
< WIRING DIAGRAM >
ELECTRONICALLY CONTROLLED POWER STEERING SYSTEM
WIRING DIAGRAM
ELECTRONICALLY CONTROLLED POWER STEERING SYSTEM
Wiring Diagram INFOID:0000000006256123
JCGWM0392GB
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ELECTRONICALLY CONTROLLED POWER STEERING SYSTEMSTC-11
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JCGWM0393GB
Revision: 2010 May2011 QX56