ON-BOARD DIAGNOSTIC SYSTEM [ELECTRONIC 4WD CONTROL SYSTEM]

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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.

― PID/data monitor function that reads out specified input/output signals.

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

• 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

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Function

Malfunction detection function

• The malfunction detection function detects malfunctions in the input/output signal system of the 4WD control module when the ignition switched ON or driving the vehicle.

• The 4WD control module performs that the 4WD 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.

Malfunction indication function

• When the malfunction detection function detects a malfunction, the 4WD warning light illuminates or flashes 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 4WD 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	4WD warning light	Description	Fail-safe	Drive cycle	Self test type^*1	Memory function
P164D:00	Illuminates	4WD control module configuration	×	—	C	×
P182F:00	Flashes	4WD control module	×	—	C	×
P187B:00	Illuminates	4WD control module	×	—	C	×
P1886:00	Illuminates	4WD control module	×	—	C	×
P1887:11	Illuminates	System wiring	×	—	C	×
P1887:12	Illuminates	System wiring	×	—	C	×
P1887:13	Illuminates	System wiring	×	—	C	×
P1887:14	Illuminates	System wiring	×	—	C	×
P1888:11	Illuminates	Differential oil temperature sensor	×	—	C	×
P1888:15	Illuminates	Differential oil temperature sensor	×	—	C	×
P188A:00	Flashes	4WD control module	×	—	C	×
U0001:88	Illuminates	CAN line	×	—	C	×
U0100:00	Not illuminate	CAN line	×	—	C	×
U0101:00	Not illuminate	CAN line	×	—	C	×
U0121:00	Not illuminate	CAN line	×	—	C	×
U0401:68	Not illuminate	Signal error from PCM	×	—	C	×
U0402:68	Not illuminate	Signal error from TCM	×	—	C	×
U0415:68	Not illuminate	Signal error from DSC HU/CM	×	—	C	×
U2100:00	Illuminates	4WD control module configuration	×	—	C	×

*1 :C: CMDTC self test

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

Fail-safe function

• When the malfunction detection function determines a malfunction, the 4WD warning light illuminates or flashes to alert the driver. At this time, the fail-safe function controls as indicated in the fail-safe function table.

Fail-safe function table

DTC	4WD control
P164D:00	Operates at initial value
P182F:00	Rear wheel torque zero (looked in 2WD)
P187B:00	Rear wheel torque zero (looked in 2WD)
P1886:00	Rear wheel torque zero (looked in 2WD)
P1887:11	Rear wheel torque zero (looked in 2WD)
P1887:12	Rear wheel torque zero (looked in 2WD)
P1887:13	Rear wheel torque zero (looked in 2WD)
P1887:14	Rear wheel torque zero (looked in 2WD)
P1888:11	Rear wheel torque zero (looked in 2WD)
P1888:15	Rear wheel torque zero (looked in 2WD)
P188A:00	Rear wheel torque zero (looked in 2WD)
U0001:88	Rear wheel torque zero (looked in 2WD)
U0100:00	Rear wheel torque zero (looked in 2WD)
U0101:00	Part of control disabled
U0121:00	Rear wheel torque zero (looked in 2WD)
U0401:68	Rear wheel torque zero (looked in 2WD)
U0402:68	Part of control disabled
U0415:68	Rear wheel torque zero (looked in 2WD)
U2100:00	Operates at initial value

Snapshot data

• The snapshot data stores the currently detected DTC data.

—: Not applicable

Snapshot data item	Unit	Definition	Data read/use method	Corresponding data monitor items
AAT	°C, °F	Ambient air temperature	—	AAT
IC_VPWR	V	Instrument cluster power supply	• The 4WD 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 4WD control module records the power supply voltage of the instrument cluster when the DTC was detected, and it is displayed in the Mazda Modular Diagnostic System (M-MDS).	—
IG-ON_TIMER	hh:mm:ss^*2	Elapsed time since ignition was switched ON Note • The instrument cluster records the elapsed time since the ignition was switched ON.	• The 4WD 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 4WD control module records the elapsed time since the ignition was switched ON when the DTC was detected, and it is displayed in the Mazda Modular Diagnostic System (M-MDS).	—
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	• Key Out: Ignition switched off • Key Recently Out (Position 0): Elapsed time within 3 s since ignition was switched 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 4WD control module constantly receives the ignition switch status sent via CAN signal from the instrument cluster. • If a DTC is detected, the 4WD control module records the ignition switch status when the DTC was detected, and it is displayed in the Mazda Modular Diagnostic System (M-MDS).	—
TOTAL_DIST	km, ft, mi	Accumulated total traveled distance from completion of vehicle until 4WD control module detects DTC (Odometer value in instrument cluster)	The distance traveled when the 4WD 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 4WD control module detects a DTC Note • When the ROOM fuse is removed, and the ignition is switched off, the time is not included in the elapsed time.	The elapsed time when the 4WD 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.	—

*1 :Fractions of seconds may be indicated after the decimal point

PID/data monitor function

• The PID/data monitor function is used for optionally selecting input/output signal monitor items preset in the 4WD control module and reading them out in real-time.

—: Not applicable

Monitor item	Unit/Operation	Test condition	Specification (Reference)
Mazda Modular Diagnostic System (M-MDS) display	Unit/Operation	Test condition	Specification (Reference)
AAT	°C, °F	This PID indicates ambient air temperature.
APP	%	This PID indicates accelerator pedal position.
CAL_TABLE	—	This PID indicates 4WD calibration table.
CUP_SOL	%	This PID indicates 4WD solenoid duty cycle.
GEAR	Unknown/1st/2nd/3rd/4th/5th/6th/7th/8th/Not in P/Park/Neutral/Drive/Reverse	This PID indicates gear position.
OIL_TEMP	°C, °F	This PID indicates differential oil temperature.
RPM	RPM	This PID indicates engine speed.
SHIFT	2Posions/P/R/N/D/S(2)/L(1)/-	This PID indicates select lever position.
TORQUE	Nm	This PID indicates total wheel torque.
VPWR	V	This PID indicates power supply voltage for 4WD control module.
WARN_LAMP	OFF/ON/Blinking	This PID indicates 4WD warning light status.
WSPD_LF	KPH, MPH	This PID indicates wheel speed.
WSPD_LR	KPH, MPH	This PID indicates wheel speed.
WSPD_RF	KPH, MPH	This PID indicates wheel speed.
WSPD_RR	KPH, MPH	This PID indicates wheel speed.

Simulation function

• The simulation function is used for optionally selecting simulation items of input/output parts preset in the 4WD control module, and to operate them regardless of control.

Simulation item

Output part

Operation

Operating condition

CUP_SOL

4WD solenoid

OFF/ON

Switch the ignition ON (engine off or on)

Simulation item	Output part	Operation	Operating condition
CUP_SOL	4WD solenoid	OFF/ON	Switch the ignition ON (engine off or on)

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 4WD control module 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 4WD control module via CAN lines.

• The 4WD 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).