ON-BOARD DIAGNOSTIC SYSTEM [DYNAMIC STABILITY CONTROL (DSC)]

id0402b2181300

OUTLINE

―  A malfunction detection function that detects abnormalities in input/output signals when the ignition switch is at the ON position.

―  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

am6zzn00003363

FUNCTION

Malfunction detection function

•  The malfunction detection function detects and displays malfunctions in the input/output signal system of the DSC HU/CM when the ignition is switched to ON.

•  When the DSC HU/CM is activated, the following malfunction detection is performed.

―  The ABS warning light, brake system warning light, DSC OFF indicator light, TCS/DSC indicator light, tire pressure monitoring system warning light and master warning light illuminate for approx. 3.0 s when the ignition is switched to ON to inspect for open circuits in the lights. At the same time, the input/output signals of each part is 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

•  When the pump motor operates, it is sound can be heard.

•  If the above malfunctions are detected, the corresponding lights are illuminated to alert the driver. DTCs can be output through the CAN_H and CAN_L of the DLC-2 using the external tester communication function. 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 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 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.

ac5wzn00001215

Fail-safe function

•  When the malfunction detection function determines a malfunction, the warning indicator light illuminates to alert the driver. At this time, the fail-safe function controls as indicated in the fail-safe function malfunction contents 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 Malfunction Contents

Status byte for DTC

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

am5ezn00002077

•  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 Mazda Modular Diagnostic System (M-MDS) when reading the DTC.

Snapshot data

Note

•  The DSC HU/CM stores the following two types of information when a DTC is detected and displays snap shot data in the M-MDS.

―  Vehicle information detected by DSC HU/CM

―  Vehicle information detected by instrument cluster and received by start stop unit via CAN signal

•  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.

PID name (definition)	Unit/Condition	Operation condition (reference)	Action
BRAKE_SW	Off/On	•  Brake pedal released: Off •  Brake pedal depressed: On	Inspect the brake switch.
BRK_F_P_R (Raw Value)	Pa, psi	•  Brake pedal depressed: Changes according to the brake fluid pressure	Inspect the brake fluid pressure sensor.
DDS_MODE	Not_Learned/Learning/Learned	•  During initialization: Not_Learned •  During learning: Learning •  Learning completed*: Learned	Perform the DTC inspection for the DSC HU/CM.
DSC_OFF_SW	Off/On	•  DSC OFF switch is released: Off •  DSC OFF switch is depressed: On	Inspect the DSC OFF switch.
DSC_ST	Off/On	•  During DSC OFF mode: Off •  Other than DSC OFF mode: On	Perform the DTC inspection for the DSC HU/CM.
LAT_ACCL_R (Raw Value)	G	•  Vehicle stopped or driving at constant speed: 0 G •  Cornering to left: Changes 0 G—positive •  Cornering to right: Changes 0 G—negative	Perform the DTC inspection for the SAS control module.
LON_ACCL_C (Calculated Value)	G	•  Vehicle stopped or driving at constant speed: 0 G •  Vehicle is driving at a acceleration: Changes 0 G—positive •  Vehicle is driving at a deceleration: Changes 0 G—negative	Perform the DTC inspection for the SAS control module.
LON_ACCL_R (Raw Value)
PMP_MT_SP	Off/On	•  Pump motor not activated: Off •  Pump motor activated: On	Inspect the DSC HU/CM.
STR_ANG_C (Calculated Value)	°	•  Steering wheel in neutral position (not turned): 0° •  Steering wheel turned to left: Changes 0°—positive •  Steering wheel turned to right: Changes 0°—negative Note •  Constantly indicates 0° until the steering wheel angle neutral position determination by the DSC HU/CM is completed. •  The steering wheel angle neutral position determination by the DSC HU/CM is completed when the vehicle is driven in a straight line at a speed of 20 km/h or more for several seconds.	Perform the DTC inspection for the PCM, DSC HU/CM, and EPS control module. If a DTC is displayed after performing the DTC inspection for the PCM, DSC HU/CM, and EPS control module, repair the malfunctioning part according to the applicable DTC troubleshooting. After performing the DTC inspection, perform the following procedures: •  Start the engine and drive the vehicle in a straight line at a speed of 20 km/h or more for several seconds. If an abnormal value is indicated after verifying the value of the STR_ANG_C again, replace the DSC HU/CM.
STR_ANG_R (Raw Value)		•  Steering wheel position when ignition is switched ON (engine off or on): 0° •  Steering wheel turned to left: Changes 0°—positive •  Steering wheel turned to right: Changes 0°—negative Note •  The signal displayed in this item is a steering angle (relative angle) signal output from the EPS control module.	Inspect the following PID. •  STR_ANG
TPMS_TYPE	No_DDS/DDS/DDS+TOM_O/DDS+TOM_EU/DDS+TOM_US	•  TPMS not equipped: No_DDS •  TPMS equipped: DDS •  TPMS equipped (Corresponding to European and U.S. regulations): DDS+TOM_O •  TPMS equipped (Corresponding to European regulations): DDS+TOM_EU •  TPMS equipped (Corresponding to U.S. regulations): DDS+TOM_US	Perform the DTC inspection for the DSC HU/CM.
V_INLET_LF	Off/On	•  Solenoid valve not activated: Off •  Solenoid valve activated: On	Inspect the DSC HU/CM.
V_INLET_LR
V_INLET_RF
V_INLET_RR
V_OUTLET_LF
V_OUTLET_LR
V_OUTLET_RF
V_OUTLET_RR
V_TRC_LF/RR	Off/On	•  Solenoid valve activated: On •  Solenoid valve not activated: Off	Inspect the DSC HU/CM.
V_TRC_RF/LR
VPWR_B_SOL	V	•  Ignition switched ON (engine off): Approx. 12.2 V •  Idling: Approx. 14.1 V	Inspect power supply circuit.
VSPD	KPH, MPH	•  Vehicle stopped: 0 KPH, 0 MPH •  Vehicle running: Vehicle speed	Inspect the DSC HU/CM.
WSPD_SEN_LF	KPH, MPH	•  Vehicle stopped: 0 KPH, 0 MPH •  Vehicle running: Vehicle speed	Inspect the front ABS wheel-speed sensor.
WSPD_SEN_LR			Inspect the rear ABS wheel-speed sensor.
WSPD_SEN_RF			Inspect the front ABS wheel-speed sensor.
WSPD_SEN_RR			Inspect the rear ABS wheel-speed sensor.
YAW_RATE_C (Calculated Value)	°/s	•  Vehicle stopped or driving straight: 0 °/s •  Cornering to left: Changes 0 °/s—positive •  Cornering to right: Changes 0 °/s—negative	Perform the DTC inspection for the SAS control module.
YAW_RATE_R (Raw Value)

Active command modes function

•  The active command modes 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 active command modes function.

Active command mode table

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 using the CAN_H and CAN_L terminals (within the DLC-2).

•  The DSC HU/CM receives the command signals of the malfunction detection function, PID/data monitor function, and the active command modes function based on the Mazda Modular Diagnostic System (M-MDS), and sends DTCs and data regarding the operating condition and 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
PID/data monitor function	Command signal to read selected monitor item	Monitored data for requested monitor item
Active command modes function	Operation command signal for selected active command modes item	Output part drive signal