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

id0602a1100900


Outline

•  The on-board diagnostic system consists of the following functions:
―  A malfunction detection function that detects abnormalities in input/output signals when the ignition switch is at the ON position.
―  A PID/data monitor function that reads out specified input/output signals.
•  The data link connector 2 (DLC-2), which groups together all the connectors used for malfunction diagnosis into a single location, has been adopted, thereby improving serviceability. Diagnosis is performed by connecting the Mazda Modular Diagnostic System (M-MDS) to the DLC-2.
•  In addition to DTC read-out, the Mazda Modular Diagnostic System (M-MDS) has following functions:
―  PID/data monitor access
―  DTC clear using the display screen of the diagnostic tester

Block diagram

am6zzn00003253


Function


Malfunction detection function

•  The malfunction detection function detects malfunctions in the input/output signal system of the EPS control module when the ignition switched ON or driving the vehicle.


Malfunction indication function

•  When the malfunction detection function detects a malfunction, the power steering malfunction indicator light illuminates to alert 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 function and fail-safe function.
•  The power steering malfunction indicator light may not illuminate depending on the detected malfunction.


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 switch has been switched 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.

DTC table

X: Applicable
—: Not applicable

DTC

Power steering malfunction indicator light

Description

Fail-safe

Drive cycle

Self test type*1

Memory function
C200B:02
Illuminates
Torque sensor
X
—
C, D
X
C200B:16
Illuminates
Torque sensor
X
—
C, D
X
C200B:1C
Illuminates
Torque sensor
X
—
C, D
X
C200B:49
Illuminates
Torque sensor
X
—
C, D
X
C200B:62
Illuminates
Torque sensor
X
—
C, D
X
C200B:64
Illuminates
Torque sensor
X
—
C, D
X
C200B:85
Illuminates
Torque sensor
X
—
C, D
X
C200C:1C
Illuminates
Torque sensor
X
—
C, D
X
C200D:1C
Illuminates
Resolver sensor
X
—
C, D
X
C200D:64
Illuminates
Resolver sensor
X
—
C, D
X
U0001:88
Illuminates
CAN system communication error
X
—
C, D
X
U0100:00
Illuminates
Communication error to PCM
X
—
C, D
X
U0121:00
—
Communication error to DSC HU/CM
X
—
C, D
X
U0126:00
—
Communication error to SAS control module
X
—
C, D
X
U0155:00
—
Communication error to instrument cluster
X
—
C, D
X
U0214:00
—
Communication error to start stop unit
X
—
C, D
X
U023A:00
—
Communication error to forward sensing camera (FSC)
X
—
C, D
X
U0338:00
—
Signal error from start stop unit
X
—
C, D
X
U0401:00
Illuminates
Signal error from PCM (vehicle speed)
X
—
C, D
X
—
Signal error from PCM (engine speed)
X
—
C, D
X
—
Signal error from PCM (i-stop status)
X
—
C, D
X
U0415:00
—
Signal error from DSC CM
X
—
C, D
X
U0423:00
—
Signal error to instrument cluster (ignition switch status)
X
—
C, D
X
U0428:00
—
Signal error to SAS control module
X
—
C, D
X
U0515:00
—
Signal error to start stop unit
X
—
C, D
X
U053B:00
Illuminates
Signal error to forward sensing camera (FSC)
X
—
C, D
X
U053B:61
Illuminates
Forward sensing camera (FSC)
X
—
C, D
X
U053B:82
Illuminates
Signal error to forward sensing camera (FSC)
X
—
C, D
X
U053B:83
Illuminates
Signal error to forward sensing camera (FSC)
X
—
C, D
X
U2011:18
Illuminates
EPS motor
X
—
C, D
X
U2011:19
Illuminates
EPS motor
X
—
C, D
X
U2011:1C
Illuminates
EPS motor
X
—
C, D
X
U2011:62
Illuminates
EPS motor
X
—
C, D
X
U2011:72
Illuminates
EPS motor
X
—
C, D
X
U2011:92
Illuminates
EPS motor
X
—
C, D
X
U2300:54
—
EPS configuration
X
—
C, D
X
U2300:55
Illuminates
EPS configuration
X
—
C, D
X
U2300:56
—
EPS configuration
X
—
C, D
X
U3000:16
Illuminates
EPS control module
X
—
C, D
X
U3000:1C
Illuminates
EPS control module
X
—
C, D
X
U3000:28
Illuminates
EPS control module
X
—
C, D
X
U3000:41
Illuminates
EPS control module
X
—
C, D
X
U3000:46
—
EPS control module
X
—
C, D
X
U3000:47
Illuminates
EPS control module
X
—
C, D
X
U3000:49
Illuminates
EPS control module
X
—
C, D
X
U3000:4B
—
EPS control module
X
—
C, D
X
U3000:61
Illuminates
EPS control module
X
—
C, D
X
U3000:73
Illuminates
EPS control module
X
—
C, D
X
U3000:96
Illuminates
EPS control module
X
—
C, D
X
U3003:16
Illuminates
Battery power supply
X
—
C, D
X
U3003:17
Illuminates
Battery power supply
X
—
C, D
X

*1  :C: CMDTC self test, D: ODDTC self test


Status byte for DTC

•  The status byte is the two-digit code (two digits after hyphen (-)) after the seven-digit DTC.
am2zzn00002656
•  The status byte is a code which indicates the pending code, current/past malfunction status, or warning illumination status.
•  The status byte can be read by performing a CMDTC self test using the Mazda Modular Diagnostic System (M-MDS).
•  For details on the status byte, refer to the explanation on the M-MDS when reading the DTC.


Fail-safe function

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

Fail-safe Function Table

DTC

Fail-safe control status
C200B:02
Control disabled
C200B:16
Control disabled
C200B:1C
Control is maintained in the backup control
C200B:62
Control disabled
C200B:64
Inhibits normal control, switches to backup control, and controls electric power steering so that steering assist can be maintained
C200C:1C
Control is maintained in the backup control
C200D:1C
Control is maintained in the backup control
C200D:64
Control disabled
U0001:88
Control enabled
U0100:00
Control is maintained by gradually changing the controlled vehicle speed and maintained in fail mode
U0121:00
Control enabled
U0126:00
Control enabled
U0155:00
Control enabled
U0214:00
Control enabled
U023A:00
Control enabled
U0338:00
Control enabled
U0401:00
•  Vehicle speed signal malfunction
―  Control is maintained by gradually changing the controlled vehicle speed and maintained in fail mode
•  Engine speed signal malfunction
―  Control enabled
•  i-stop status signal malfunction
―  EPS i-stop control is not operated, and normal control is maintained
U0415:00
Control enabled
U0423:00
Control enabled
However, control is maintained in the backup control if the engine speed is the specified value of less
U0428:00
Control enabled
U0515:00
Control enabled
U053B:00
Control enabled
U053B:61
Control enabled
U053B:82
Control enabled
U053B:83
Control enabled
U2011:19
Control disabled
U2011:1C
Control disabled
U2011:62
Control disabled
U2011:72
•  Phase 1 open circuit malfunction is detected in the EPS motor
―  Control is maintained in the backup control
•  Other malfunction detected in EPS motor internal circuit
―  Control disabled
U2011:92
Control disabled
U2300:54
Control enabled
U2300:55
Control enabled
U2300:56
Control enabled
U3000:16
Control disabled
U3000:1C
Control disabled
U3000:28
Control disabled
U3000:41
Control disabled
U3000:46
Control is maintained in fail mode
U3000:47
Control disabled
U3000:49
Control disabled
U3000:4B
Control is maintained in fail mode
U3000:61
Control disabled
U3000:73
Control disabled
U3000:96
Control disabled
U3003:16
Control is maintained by gradually decreasing the motor control current
However, control is inhibited if the power supply voltage is the specified value of less
U3003:17
Control disabled


Snapshot Data

•  The snapshot data stores the currently detected DTC data.

—: Not applicable

Snapshot data item

Unit

Data contents

Data read/use method

Corresponding data monitor items
AAT
°C, °F
Ambient air temperature
—
—
APP_STATUS
Accelerator Pedal Off/
Under 20%/
Over 20%/
FAIL
Accelerator pedal position
—
—
CEN_TRQ_S
Nm
Center value of torque sensor
CEN_TRQ_S
CEN_TRQ_S
CFG_STATUS
Config Complete/
Not Configured/
Config Error
Instrument cluster configuration status
—
—
ECT_STATUS
Under 0 degrees C/
0 - Under 80 degrees C/
Over 80 degrees C/
FAIL
Engine coolant temperature status
—
—
ECU_IN_TMP
°C, °F
ECU internal temperature
ECU_IN_TMP
ECU_IN_TMP
ENG_RPM
RPM
Engine speed
ENG_RPM
ENG_RPM
IC_VPWR
V
Instrument cluster power supply
•  The EPS control module constantly receives the power supply voltage value of the instrument cluster sent via CAN signal from the instrument cluster.
•  If a DTC is detected, the EPS control module records the power supply voltage of the instrument cluster when the DTC was detected, and it is displayed in the M-MDS.
—
IG-ON_TIMER
hh:mm:ss*1
Elapsed time since ignition was switched ON
Note
•  The instrument cluster records the elapsed time since the ignition was switched ON.
•  The EPS control module constantly receives the elapsed time since the ignition was switched ON sent via CAN signal from the instrument cluster.
•  If a DTC is detected, the EPS control module records the elapsed time since the ignition was switched ON when the DTC was detected, and it is displayed in the M-MDS.
—
LAS_CUR*3
A
Lane-keep assist system control output current
LAS_CUR
LAS_CUR
MT_CURRENT
A
Motor current
MT_CURRENT
MT_CURRENT
OH_CR_C
No/Yes
Current overheat protection control (complete)
OH_CR_C
OH_CR_C
OH_CR_M
No/Yes
Current overheat protection control (middle)
OH_CR_M
OH_CR_M
OH_HIST_C
No/Yes
History of overheat protection control (complete)
OH_HIST_C
OH_HIST_C
OH_HIST_M
No/Yes
History of overheat protection control (middle)
OH_HIST_M
OH_HIST_M
OH_IG_CNT_C
—
The number of times the ignition is switched ON during the period from when overheat protection control (complete) is finished to the time the next overheat protection control (complete) is started
•  Displays a maximum number of 255 times in which the ignition is switched ON until the first overheat protection control (complete) is started.
•  During overheat protection control (complete), the number of times the ignition is switched ON is not counted, and 0 is displayed.
OH_IG_CNT_C
OH_IG_CNT_C
OH_IG_CNT_M
—
The number of times the ignition is switched ON during the period from when overheat protection control (middle) is finished to the time the next overheat protection control (middle) is started
•  Displays a maximum number of 255 times in which the ignition is switched ON until the first overheat protection control (middle) is started.
•  During overheat protection control (middle), the number of times the ignition is switched ON is not counted, and 0 is displayed.
OH_IG_CNT_M
OH_IG_CNT_M
PWR_MODE_KEY
Key Out/
Key Recently Out/
Key Approved(Position 0)/
Post Accessory (Position 0)/
Accessory (Position 1)/
Post Ignition (Position 1)/
Ignition On (Position 2)/
Running (Position 2)/
Running - Starting In Progress (Position 2)/
Crank (Position 3)
•  Key Out: Ignition switched to off
•  Key Recently Out (Position 0): Elapsed time within 3 s since ignition was switched to off
•  Accessory (Position 1): Ignition is switched to ACC
•  Post Ignition (Position 2): Elapsed time within 3 s since ignition was switched ON
•  Ignition On (Position 2): Ignition switched ON (engine off)
•  Running (Position 2): Ignition switched ON (engine on)
•  Running - Starting: Cranking condition
•  The EPS control module constantly receives the ignition switch status sent via CAN signal from the instrument cluster.
•  If a DTC is detected, the EPS control module records the ignition switch status when the DTC was detected, and it is displayed in the M-MDS.
—
RPM_STATUS
Engine Stop/
Under 1500rpm/
Over 1500rpm/
FAIL
Engine RPM status
•  The EPS control module constantly receives the ignition switch status sent via CAN signal from the instrument cluster.
•  If a DTC is detected, the EPS control module records the ignition switch status when the DTC was detected, and it is displayed in the M-MDS.
TACHOMTR*2
SHIFT_STATUS
P/N
D/
R/
FAIL
Shift position status
•  The EPS control module constantly receives the selector lever position sent via CAN signal from the instrument cluster.
•  If a DTC is detected, the EPS control module records the selector lever position when the DTC was detected, and it is displayed in the M-MDS.
—
STR_ANG_EST*3
°
Steering wheel angle (estimated absolute angle)
STR_ANG
STR_AB_EST
STR_ANG
°
Steering wheel angle
STR_ANG
STR_ANG
STR_ROT_SPD
°/s
Steering wheel rotation speed
STR_ROT_SPD
STR_ROT_SPD
STR_TRQ_S_M
Nm
Steering shaft torque (Main)
STR_TRQ_S_M
STR_TRQ_S_M
STR_TRQ_S_S
Nm
Steering shaft torque (Sub)
STR_TRQ_S_S
STR_TRQ_S_S
TOTAL_DIST
km, ft, mi
Accumulated total traveled distance from completion of vehicle until EPS control module detects DTC (Odometer value in instrument cluster)
The distance traveled when the EPS control module detected a DTC can be calculated by performing the following procedure.
1.  Verify the odometer value in the instrument cluster.
2.  Verify the snap shot data item TOTAL_DIST.
3.  Subtract 2 from 1.
—
TOTAL_TIME
hh:mm:ss*1
Accumulated total elapsed time since vehicle completion until EPS control module detects a DTC
Note
•  When the ROOM removed, and the ignition is switched to off, the time is not included in the elapsed time.
The elapsed time when the EPS control module detected a DTC can be calculated by performing the following procedure.
1.  Verify the PID item TOTAL_TIME of the instrument cluster.
2.  Verify the snap shot data item TOTAL_TIME.
3.  Subtract 2 from 1.
TOTAL_TIME*2
VPWR
V
Power supply
VPWR
VPWR
VSPD
KPH, MPH
Vehicle speed
VSPD
VSPD
VSPD_STATUS
Stop/
0 - 10km/h/
Over 10km/h/
FAIL
Vehicle speed status
•  The EPS control module constantly receives the vehicle speed sent via CAN signal from the instrument cluster.
•  If a DTC is detected, the EPS control module records the vehicle speed when the DTC was detected, and it is displayed in the M-MDS.
SPEEDOMTR*2

*1  :The seconds may be indicated after the decimal point.
*2  :Instrument cluster PID.
*3  :With lane-keep assist system.


External Tester Communication Function

Outline
•  The external tester communication function enables communication of diagnostic data (DTC read-outs, input/output signal read-outs) between the EPS control module (CM) and an external tester.
•  By connecting the Mazda modular diagnostic system (M-MDS) to the DLC-2, diagnostic data can be sent and received between the Mazda modular diagnostic system (M-MDS) and the EPS control module via CAN lines.
•  The EPS control module receives the command signals of the malfunction detection function and PID/data monitor function from the Mazda modular diagnostic system (M-MDS), and sends DTCs and data regarding the operating status of each input/output part to the Mazda modular diagnostic system (M-MDS).

Diagnostic function name

Signal received

Signal sent
Malfunction detection function
DTC verification signal
Diagnostic trouble code
PID/DATA monitor function
Command signal to read selected monitor item
Monitored data for requested monitor item