ON-BOARD DIAGNOSTIC SYSTEM [EVP CONTROL UNIT]

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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 EVP control unit when the ignition switched ON or driving the vehicle.

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 EVP control unit 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

DTC detection logic and conditions 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.

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 EVP control unit and reading them out in real-time.

Simulation function

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

Simulation item	Operation	Output part	Operating condition
VPS_FBK	Off/On	Electric vacuum pump	For maximum of 30 s when all of the following conditions are met with ignition switched ON (engine off or on) •  Vehicle speed 6 km/h {3 mph} or less •  Operation of electric vacuum pump not inhibited by fail-safe

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 EVP control unit 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 EVP control unit via CAN lines.

•  The EVP control unit 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