ON-BOARD DIAGNOSTIC SYSTEM [DSC HU/CM]

id040262181300

Outline

―  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.

―  A simulation function that allows for override operation of output parts.

―  PID/data monitor access

―  DTC clear using the display screen of the diagnostic tester

Block diagram

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Function

Malfunction detection function

•  The malfunction detection function detects malfunctions in the input/output signal system of the DSC HU/CM when the ignition switched ON or driving the vehicle.

•  The DSC HU/CM performs the following malfunction detections:

―  The brake system warning light, ABS warning light, TCS/DSC indicator light, DSC OFF indicator light, and Tire Pressure Monitoring System (TPMS) warning light illuminate for approx. 3.0 s when the ignition is switched ON. At the same time, the input/output signals of each part are monitored for malfunction diagnosis.

―  After starting to drive, the first time the vehicle speed is approx. 10 km/h {6.2 mph} or more the pump motor is operated and malfunction diagnosis is performed again. The input/output signals of each part are then constantly monitored and malfunctions are diagnosed.

Note

•  The sound of the pump motor operation can be heard.

Malfunction display function

•  When the malfunction detection function detects a malfunction, the corresponding lights illuminate 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.

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 DSC HU/CM 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

Status byte for DTC

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

Fail-safe function

•  When the malfunction detection function determines a malfunction, the corresponding lights illuminates to alert the driver. At this time, the fail-safe function controls as indicated in the fail-safe function table.

Warning

•  If EBD control is prohibited, the rear wheels could lock-up before the front wheels. If this occurs, the vehicle could yaw and become unstable. Therefore, always inspect the system immediately if EBD control is prohibited.

Fail-safe function table

Snapshot data

•  The snapshot data stores the currently detected DTC data.

PID/data monitor function

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

Monitor item	Unit/operation	Definition
BRAKE_SW	Off/On	Brake switch signal
BRK_F_P_C	Pa, psi	Brake fluid pressure sensor signal (calculated value)
BRK_F_P_R	Pa, psi	Brake fluid pressure sensor signal (raw value)
DDS_MODE	Not_Learned/Learning/Learned	Deflation detection system mode
DSC_OFF_SW	Off/On	DSC OFF switch signal
DSC_ST	Off/On	DSC status
LAT_ACCL_C	G	Lateral-G value (calculated value)
LAT_ACCL_R	G	Lateral-G value (raw value)
LON_ACCL_C	G	Longitudinal-G value (calculated value)
LON_ACCL_R	G	Longitudinal-G value (raw value)
P_BRAKE_SW	Off/On	Parking brake switch signal
PMP_MT	Off/On	Pump motor status
PMP_MT_SP	Off/On	Pump motor status
R_GEAR_SW	Off/On	Shift lever signal (R position)
STR_ANG_C	°	Steering wheel angle (calculated value)
STR_ANG_R	°	Steering wheel angle (raw value)
TPMS_TYPE	No_DDS/DDS/DDS+TOM_O/DDS+TOM_EU/DDS+TOM_US	Tire Pressure Monitoring System (TPMS) type
V_INLET_LF	Off/On	LF inlet solenoid valve status
V_INLET_LR	Off/On	LR inlet solenoid valve status
V_INLET_RF	Off/On	RF inlet solenoid valve status
V_INLET_RR	Off/On	RR inlet solenoid valve status
V_OUTLET_LF	Off/On	LF outlet solenoid valve status
V_OUTLET_LR	Off/On	LR outlet solenoid valve status
V_OUTLET_RF	Off/On	RF outlet solenoid valve status
V_OUTLET_RR	Off/On	RR outlet solenoid valve status
V_STB_LF/RR	Off/On	LF/RR stability control solenoid valve status
V_STB_RF/LR	Off/On	RF/LR stability control solenoid valve status
V_TRC_LF/RR	Off/On	LF/RR traction control solenoid valve status
V_TRC_RF/LR	Off/On	RF/LR traction control solenoid valve status
VPWR_B_SOL	V	Power supply
VSPD	KPH, MPH	Vehicle speed
WSPD_SEN_LF	KPH, MPH	LF ABS wheel-speed sensor signal
WSPD_SEN_LR	KPH, MPH	LR ABS wheel-speed sensor signal
WSPD_SEN_RF	KPH, MPH	RF ABS wheel-speed sensor signal
WSPD_SEN_RR	KPH, MPH	RR ABS wheel-speed sensor signal
YAW_RATE_C	°/s	Yaw rate value (calculated value)
YAW_RATE_R	°/s	Yaw rate value (raw value)

Simulation function

•  The simulation function is used for optionally selecting simulation items of input/output parts preset in the DSC HU/CM, and to operate them regardless of CM control.

•  To protect the hydraulic unit interior, operate output related parts for only 2 s or less when using the simulation function.

Simulation item	Operation	Output part	Operating condition
PMP_MT_SP	Off/On	Pump motor	Switch the ignition ON (engine off)
V_INLET_LF	Off/On	LF inlet solenoid valve	Switch the ignition ON (engine off)
V_INLET_LR	Off/On	LR inlet solenoid valve	Switch the ignition ON (engine off)
V_INLET_RF	Off/On	RF inlet solenoid valve	Switch the ignition ON (engine off)
V_INLET_RR	Off/On	RR inlet solenoid valve	Switch the ignition ON (engine off)
V_OUTLET_LF	Off/On	LF outlet solenoid valve	Switch the ignition ON (engine off)
V_OUTLET_LR	Off/On	LR outlet solenoid valve	Switch the ignition ON (engine off)
V_OUTLET_RF	Off/On	RF outlet solenoid valve	Switch the ignition ON (engine off)
V_OUTLET_RR	Off/On	RR outlet solenoid valve	Switch the ignition ON (engine off)
V_STB_LF/RR	Off/On	LF/RR stability control solenoid valve	Switch the ignition ON (engine off)
V_STB_RF/LR	Off/On	RF/LR stability control solenoid valve	Switch the ignition ON (engine off)
V_TRC_LF/RR	Off/On	LF/RR traction control solenoid valve	Switch the ignition ON (engine off)
V_TRC_RF/LR	Off/On	RF/LR traction control solenoid valve	Switch the ignition ON (engine off)

External tester communication function

•  The external tester communication function enables communication of diagnostic data (DTC read-outs, input/output signal read-outs, operation of input/output parts) between the DSC HU/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 DSC HU/CM via CAN lines.

•  The DSC HU/CM receives the command signals of the malfunction detection function, PID/data monitor function, and simulation 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	DTC(s)
PID/data monitor function	Command signal to read selected monitor item	Monitored data for requested monitor item
Simulation function	Operation command signal for selected simulation item	Output part drive signal