ON-BOARD DIAGNOSTIC SYSTEM FUNCTION [ELECTRIC POWER STEERING (EPS)]

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Malfunction Detection Function

•  The malfunction detection function detects malfunctions in the input/output signal system of the EPS control module when the ignition is at ON or driving the vehicle.
•  When the ignition is switched to ON, the EPS warning light illuminates as shown in the diagram to inspect for open circuits in the light.
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Malfunction Display Function

•  When the malfunction detection function detects a malfunction, the EPS warning light illuminates to advise the driver. Using the external tester communication function, DTCs can be output to the DLC-2 via the CAN line. At the same time, malfunction detection results are sent to the memory and fail-safe functions.

Memory Function

•  The memory function stores DTCs of malfunctions in input/output signal systems. With this function, once a DTC is stored it is not cleared after the ignition has been switched to off, even if the malfunctioning signal system has returned to normal.
•  Since the EPS control module has a built-in non-volatile memory, DTCs are not cleared even if the battery is removed. Therefore, it is necessary to clear the memory after performing repairs. Refer to the Workshop Manual for the DTC clearing procedure.

Fail-safe Function

•  When the malfunction detection function determines a malfunction, the EPS warning light illuminates or flashes to advise the driver. At this time, the fail-safe function disables system control or gradually reduces the assist power.

Fail-safe Function Table

System Malfunction Location

DTC (Mazda Modular Diagnostic System (M-MDS) display)

Fail-safe function

EPS warning light illumination status

Control status
Torque sensor
C200B:1C
Illuminated
Control disabled
Torque sensor
C200B:1E
Illuminated
Control disabled
Torque sensor
C200B:25
Illuminated
Control disabled
EPS system (neutral position setting not performed)
C200B:54
Illuminated
Control enabled*1
Torque sensor
C200B:62
Illuminated
Control disabled
Resolver sensor
C200D:1C
Illuminated
Control disabled
Resolver sensor
C200D:62
Illuminated
Control disabled
CAN system communication error
U0001:88
Illuminated
Control enabled*1
CAN system communication error
U0100:00
Illuminated*2
Control enabled*1
EPS configuration
U0300:00
Illuminated
Control disabled
EPS configuration
U0300:85
Illuminated
Control disabled
CAN system communication error (If vehicle speed signal is abnormal)
U0401:00
Illuminated*2
Control enabled*3
CAN system communication error (If engine speed signal is abnormal)
Illuminated*4, *5
Control enabled*6
EPS motor
U2011:1C
Illuminated
Control disabled
EPS motor
U2011:19
Illuminated
Control disabled
EPS motor
U2011:61
Illuminated
Control disabled
EPS motor
U2011:62
Illuminated
Control disabled
EPS motor
U2011:64
Illuminated
Control disabled
EPS motor
U2011:72
Illuminated
Control disabled
EPS configuration
U2100:00
Illuminated
Control disabled
EPS control module
U3000:16
Illuminated
Control disabled
EPS control module
U3000:38
Illuminated
Control disabled
EPS control module
U3000:41
Illuminated
Control disabled
EPS control module
U3000:46
Illuminated
Control enabled*1
EPS control module
U3000:49
Illuminated
Control disabled
EPS control module
U3000:62
Illuminated
Control disabled
EPS control module
U3000:73
Illuminated
Control disabled
EPS control module
U3000:96
Illuminated
Control disabled
EPS control module
U3000:4B
Illuminated
Control enabled*7
Battery power supply
U3003:16
Illuminated
Control disabled
Battery power supply
U3003:17
Illuminated
Control disabled

*1  :Control is maintained in fail mode.
*2  :After switching to fail mode, the EPS warning light is illuminated.
*3  :Control is maintained in fail mode (controlled by specified vehicle speed signal).
*4  :The EPS warning light is illuminated if a malfunction is detected before the engine is started.
*5  :The EPS warning light is not illuminated if a malfunction is detected after the engine is started.
*6  :Control is maintained in fail mode (controlled by engine speed signal last received).
*7  :Control is maintained in fail mode until the temperature in the EPS control module decreases to 120°C {248°F} or less.