ELECTRIC POWER STEERING-ECU (EPS-ECU)



The EPS-ECU includes an input interface circuit, a microprocessor, an output drive circuit, a power relay and a motor line relay. It also integrates a self-diagnostic function, and illuminates the warning lamp on the combination meter when a trouble occurs. At the same time, it sends diagnosis code(s) to the diagnosis connector.

CAN communication


The EPS-ECU communicates with the other ECUs and other units through CAN communication to control the steering system.
Input signals
Sent to
Engine-ECU
4WD-ECU
Combination meter (via the ETACS-ECU)
ETACS-ECU
Engine speed
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Vehicle speed
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-
-
-
Additional torque

·


Distance information (diagnosis additional information)
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-
·
-
Vehicle information (diagnosis control)
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-
-
·
note Indicates items which send and receive data through CAN communication.
Output signal name
Received by
Engine-ECU
Combination meter (via the ETACS-ECU)
Diagnosis connector
Motor current signal
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-
-
EPS warning lamp illumination request signal
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·
-
Diagnosis code signal
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-
·
Service data output signal
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-
·
note Indicates items which send and receive data through CAN communication.

Fail-safe function


If the EPS-ECU detects any malfunction, it illuminates the EPS warning lamp, deactivates the EPS functions, and then switches the steering system into manual mode.

DIAGNOSIS FUNCTION


The EPS-ECU has the following functions to make system checks easier.

All the above items can be diagnosed using MUT-III.

Diagnosis code set


There are 29 diagnostic items. Since all the diagnostic results are recorded in volatile memory (EEPROM*), they are stored in the memory even though the battery terminals are disconnected.
note
  • *EEPROM (Electrical Erasable & Programmable ROM): Special type of memory that can be programmed or erased electrically.
  • For diagnosis items, refer to Workshop Manual.

Service data output


Using M.U.T.-III, the input data sent from the sensors and motors can be read.
note For service data items, refer to Workshop Manual.