Nissan Sentra Service Manual: System
EPS system
EPS SYSTEM : System Description
SYSTEM DIAGRAM
DESCRIPTION
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EPS control unit performs an arithmetical operation on data, such as steering wheel turning force (sensor signal) from the torque sensor, vehicle speed signal, etc. Then it generates an optimum assist torque signal to the EPS motor according to the driving condition.
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In case of a malfunction in the electrical system, the fail-safe function stops output signals to the EPS motor. Refer to STC-9, "EPS SYSTEM : Fail-Safe".
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EPS control unit decreases the output signal to EPS motor while extremely using the power steering function (e.g., full steering) consecutively for protecting EPS motor and EPS control unit (Overload protection control). Refer to STC-13, "Protection Function".
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Extensive steering at low speed will cause the EPS control unit and EPS motor to heat up, once temperature reaches critical point EPS control unit will reduce current to reduce heat up. System will recover as temperature lowers (reduced or no assistance).
EPS Warning lamp indication
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Turn ON when there is a malfunction in EPS system. If indicates that fail-safe mode is engaged and enters a manual steering state (Control turning force steering wheel becomes heavy).
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Also turns ON when ignition switch is turned ON, for purpose of lamp check. Turns OFF after the engine starts, if system is normal.
CAUTION:
EPS warning lamp also turns ON due to data reception error, CAN communication error etc.
EPS SYSTEM : Fail-Safe
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If any malfunction occurs in the system and control unit detects the malfunction, EPS warning lamp on combination meter turns ON to indicate system malfunction.
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When EPS warning lamp is ON, the system enters into a manual steering state. (Control turning force steering wheel becomes heavy.)
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Under abnormal vehicle speed signal conditions, vehicle speed is judged as constant.
EPS SYSTEM : Protection Function
EPS control unit decreases the output signal to EPS motor while extremely using the power steering function (e.g., full steering) consecutively for protecting EPS motor and EPS control unit (Overload protection control).
While activating overload protection control, the assist torque gradually decreases, and the steering wheel turning force becomes heavy. The normal assist torque is recovered if the steering wheel is not turned for a while.
Warning/indicator/chime list
WARNING/INDICATOR/CHIME LIST : Warning Lamp/Indicator Lamp
Component parts
Component Parts Location
EPS control unit (view with steering
column removed from vehicle)
EPS motor (view with steering column
removed from vehicle)
Torque sensor (view with ...
Diagnosis system (EPS control unit)
CONSULT Function
FUNCTION
CONSULT can display each diagnostic item using the diagnostic
test modes shown following.
Diagnostic test mode
Function
ECU identification
The part ...
Other materials:
Basic inspection
Work Procedure
1.INSPECTION START
Check service records for any recent repairs that may indicate a related
malfunction, or a current need for
scheduled maintenance.
Open engine hood and check the following:
Harness connectors for improper connections
Wiring harness for improper c ...
Precaution
Precaution for supplemental restraint system (srs)
"air bag" and "seat belt pre-tensioner"
The Supplemental Restraint System such as “AIR BAG” and “SEAT BELT
PRE-TENSIONER”, used along
with a front seat belt, helps to reduce the risk or severity of injur ...
A-bag branch line circuit
Diagnosis procedure
Warning:
Always observe the following items for preventing accidental
activation.
Before servicing, turn ignition switch off, disconnect battery
negative terminal, and wait 3 minutes
or more. (To discharge backup capacitor.)
Never use unspecified tester or other me ...
