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

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Outline

• The on-board diagnostic system consists of a malfunction detection system that detects abnormalities in input/output signals when the ignition switch is at the ON position, a 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) is used to clear DTCs using the display screen of the diagnostic tester, and to access the PID/data monitor, providing enhanced malfunction diagnosis and improved serviceability.

Block diagram

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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 display function

• When the malfunction detection function detects a malfunction, the power steering malfunction indicator light illuminates or flashes 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.

• 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

×: Applicable

—: Not applicable

DTC	Power steering malfunction indicator light illumination status	Diagnosis system component	Fail-safe	Drive cycle	Self test type^*1	Memory function
M-MDS		Diagnosis system component	Fail-safe	Drive cycle	Self test type^*1	Memory function
C200B:02	Illuminated	Torque sensor	×	—	C, D	×
C200B:16	Illuminated	Torque sensor	×	—	C, D	×
C200B:1C	Illuminated	Torque sensor	×	—	C, D	×
C200B:62	Illuminated	Torque sensor	×	—	C, D	×
C200B:64	Illuminated	Torque sensor	×	—	C, D	×
C200B:85	Illuminated	Torque sensor	×	—	C, D	×
C200C:1C	Illuminated	Torque sensor	×	—	C, D	×
C200D:1C	Flashes/Illuminated*²	Resolver sensor	×	—	C, D	×
C200D:64	Illuminated	Resolver sensor	×	—	C, D	×
U0001:88	Illuminated	CAN system communication error	×	—	C, D	×
U0100:00	Illuminated	Communication error to PCM	×	—	C, D	×
U0121:00	—	Communication error to DSC CM	×	—	C, D	×
U0155:00	—	Communication error to instrument cluster	×	—	C, D	×
U0214:00	—	Communication error to start stop unit	×	—	C, D	×
U0338:00	—	Signal error from start stop unit	×	—	C, D	×
U0401:00	Illuminated	Signal (vehicle speed) error from PCM	×	—	C, D	×
U0401:00	—	Signal (engine speed) error from PCM	×	—	C, D	×
U0415:00	—	Signal error from DSC CM	×	—	C, D	×
U0423:00	—*³	Signal (engine switch status) error from instrument cluster	×	—	C, D	×
U0515:00	—	Signal error from start stop unit	×	—	C, D	×
U2011:19	Illuminated	EPS motor	×	—	C, D	×
U2011:1C	Illuminated	EPS motor	×	—	C, D	×
U2011:62	Illuminated	EPS motor	×	—	C, D	×
U2011:72	Illuminated	EPS motor	×	—	C, D	×
U2011:92	Illuminated	EPS motor	×	—	C, D	×
U2300:54	—	EPS configuration	×	—	C, D	×
U2300:55	Illuminated	EPS configuration	×	—	C, D	×
U2300:56	—	EPS configuration	×	—	C, D	×
U3000:16	Illuminated	EPS CM	×	—	C, D	×
U3000:1C	Illuminated	EPS CM	×	—	C, D	×
U3000:28	Illuminated	EPS CM	×	—	C, D	×
U3000:41	Illuminated	EPS CM	×	—	C, D	×
U3000:46	—	EPS CM	×	—	C, D	×
U3000:47	Illuminated	EPS CM	×	—	C, D	×
U3000:49	Illuminated	EPS CM	×	—	C, D	×
U3000:4B	—	EPS CM	×	—	C, D	×
U3000:61	Illuminated	EPS CM	×	—	C, D	×
U3000:73	Illuminated	EPS CM	×	—	C, D	×
U3000:96	Illuminated	EPS CM	×	—	C, D	×
U3003:16	Illuminated	Battery power supply	×	—	C, D	×
U3003:17	Illuminated	Battery power supply	×	—	C, D	×

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

*2 :If the EPS CM detects an internal circuit malfunction in the resolver sensor, it flashes the power steering malfunction indicator light. At this time, if EPS system internal temperature increases, the assist force gradually weakens. Then if assist force decreases below the specified value, the power steering malfunction indicator light switches from flashing to illumination.

*3 :If the EPS CM detects the signal that a engine speed is below the specified value, it illuminates the power steering malfunction indicator light.

Status byte for DTC

• The status byte is the two-digit code (two digits after hyphen (-)) after the DTC.

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• 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.

DTC 7-digit code definition

• When related systems or components have failed, the CM stores the DTC of the malfunctioning part in the CM memory, and allows for the retrieval of the store data using scanning tool when necessary. The DTCs are indicated using seven digits. Each digit indicates the following.

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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
M-MDS	Fail-safe control status
C200B:02	Control disabled
C200B:16	Control disabled
C200B:1C	Control disabled
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
C200B:85	Control disabled
C200C:1C	Control disabled
C200D:1C	Control is maintained in the backup control and EPS warning alarm is sounded ― If EPS system internal temperature increases above the specified value, the EPS CM disables assistance and stops the EPS warning alarm
C200D:64	Control disabled
U0001:88	Control enabled
U0100:00	Control is maintained by gradually changing the controlled vehicle speed and setting it to 100 km/h {62.1 mph}
U0121:00	Control enabled
U0155:00	Control enabled
U0214:00	Control enabled
U0338:00	Control enabled
U0401:00	• Vehicle speed signal malfunction ― Control is maintained by gradually changing the controlled vehicle speed and setting it to 100 km/h {62.1 mph} • Engine speed signal malfunction ― Control enabled
U0415:00	Control enabled
U0423:00	Control enabled ― If the EPS CM detects the signal that a engine speed is below the specified value, it disables assistance
U0515:00	Control enabled
U2011:19	Control disabled
U2011:1C	Control disabled
U2011:62	Control disabled
U2011:72	• An open circuit malfunction is detected in one phase of the three-phase stator 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	Definition	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
CFG_STATUS	Config Complete/ Not Configured/ Config Error	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
ENG_RPM	RPM	Engine speed	ENG_RPM
IC_VPWR	V	Instrument cluster power supply	—
IG-ON_TIMER	hh:mm:ss	Times since ignition switch ON	—
LAS_CUR	A	Lane-keep assist system control output current	—
MT_CURRENT	A	Motor current	MT_CURRENT
OH_CR_C	No/Yes	Current overheat protection control (complete)	OH_CR_C
OH_CR_M	No/Yes	Current overheat protection control (middle)	OH_CR_M
OH_HIST_C	No/Yes	History of overheat protection control (complete)	OH_HIST_C
OH_HIST_M	No/Yes	History of overheat protection control (middle)	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_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
PWR_MODE_KEY	Key Out/Key Recently Out (Position 0)/Accessory (Position 1)/Post Ignition (Position 2)/Ignition On (Position 2)/Running (Position 2)/Running - Starting	Power mode key state	—
RPM_STATUS	Engine Stop/ Under 1500 rpm/ Over 1500 rpm/ FAIL	Engine RPM status	—
SHIFT_STATUS	P/N D/ R/ FAIL	Shift position status	—
STR_ANG_EST	°	Steering wheel angle (estimated absolute angle)	STR_AB_EST
STR_ANG	°	Steering wheel angle	STR_ANG
STR_ROT_SPD	°/s	Steering wheel rotation speed	STR_ROT_SPD
STR_TRQ_S_M	Nm	Steering shaft torque (Main)	STR_TRQ_S_M
STR_TRQ_S_S	Nm	Steering shaft torque (Sub)	STR_TRQ_S_S
TOTAL_DIST	km, ft, mi	Total distance	—
TOTAL_TIME	hh:mm:ss	Total time	—
VPWR	V	Power supply	VPWR
VSPD	KPH, MPH	Vehicle speed	VSPD
VSPD_STATUS	Stop/ 0 - 10 km/h/ Over 10 km/h/ FAIL	Vehicle speed status	—

PID/Data Monitor Function

• The PID/data monitor function is used for optionally selecting input/output signal monitor items preset in the EPS control module (CM) and reading them out in real-time.

—: Not applicable

Monitor item (Mazda Modular Diagnostic System (M-MDS) display)	Data contents	Unit/operation
CEN_TRQ_S	• Torque sensor neutral position: Near 0 Nm	Nm
ECU_IN_TMP	• Displays temperature of board in EPS control module: -40°C—+215°C {-40°F—419°F}	°C, °F
ENG_RPM	• Engine stopped: 0 RPM • Engine rotating at 3,000 RPM: 3,000 RPM	RPM
MT_CURRENT	• When not steered: Near 0 A • Steered: Changes to positive or negative	A
OH_CR_C	• Overheat protection control (complete) is operating	Yes/No
OH_CR_M	• Overheat protection control (complete) is not operating	Yes/No
OH_HIST_C	• Overheat protection control (middle) is operating	Yes/No
OH_HIST_M	• Overheat protection control (middle) is not operating	Yes/No
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_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.	—
STR_AB_EST	• Steering wheel in neutral position (not turned): 0° • Steered left: Changes to 0°—Positive • Steered right: Changes to 0°—Negative Note • The signal displayed in this item is a estimated absolute steering angle signal output.	°
STR_ANG	• Steering wheel position when ignition is switched ON (engine off or on): 0° • Steered left: Changes to 0°—Positive • Steered right: Changes to 0°—Negative Note • The signal displayed in this item is a steering angle (relative angle) signal output.	°
STR_ROT_SPD	• Not steered: Near 0 °/s • Steered: Changes according to steering speed	°/s
STR_TRQ_S_M	• Not steered: Near 0 Nm • Steered left: Changes to 0 Nm—Positive • Steered right: Changes to 0 Nm—Negative	Nm
STR_TRQ_S_S	• Not steered: Near 0 Nm • Steered left: Changes to 0 Nm—Positive • Steered right: Changes to 0 Nm—Negative	Nm
VPWR	• Engine stopped: Approx. 12 V • Idling: Approx. 14 V	V
VSPD	• Vehicle stopped: 0 KPH, 0 MPH • Vehicle speed 20 km/h {12 mph}: 20 KPH, 12 MPH	KPH, MPH

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.

Connections/Communication Contents

	External tester
	Mazda modular diagnostic system (M-MDS)
	Connection	Communication method
On-board diagnostic (malfunction detection) function	Input/output: CAN_H (HS), CAN_L (HS)	Serial communication
PID/DATA monitor function	Input/output: CAN_H (HS), CAN_L (HS)	Serial communication

Serial communication

• Serial communication (two-way communication) allows for multiple data to be sent and received instantly along the same line.

• 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 CM via CAN lines.

• The EPS CM 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

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