Mazda 2006 MX-5 Service Highlights page 221

ON-BOARD DIAGNOSTIC SYSTEM FUNCTION (ABS, DYNAMIC STABILITY CONTROL)
Malfunction Detection Function
• The malfunction detection function detects malfunctions in the input/output signal system of the ABS HU/CM
(vehicles with ABS) or DSC HU/CM (vehicles with DSC) when the ignition switch is at the ON position.
• When the ABS HU/CM and DSC HU/CM are started up, the following malfunction detections are performed.
ABS HU/CM
— The ABS and brake system warning lights illuminate for approx. 3 s when the ignition switch is turned to
the ON position. At the same time, the fail-safe relay is operated, and 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.
DSC HU/CM
— The ABS and brake system warning lights, DSC OFF and DSC indicator lights illuminate for approx. 3 s
when the ignition switch is turned to the ON position. At the same time, the fail-safe relay is operated, and
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.
• When malfunctions are detected, the corresponding lights are illuminated to alert the driver. Using the external
tester communication function, DTCs can be output through the CAN_H and CAN_L of the DLC-2. 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 switch has been turned off (LOCK position), even if the
malfunctioning signal system has returned to normal.
• Since the ABS HU/CM or 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.
Fail-safe Function
• When the malfunction detection function determines a malfunction, each light illuminates to advise the driver.
At this time, the fail-safe function controls the ABS, EBD, TCS* and DSC* as shown in the fail-safe function
table.
*: Only vehicles with DSC
Warning
• If EBD control is suspended the rear wheels could lock-up before the front wheels. If this occurs,
the vehicle could swerve and become unstable. Therefore always inspect the system immediately
if EBD control is suspended.
ON-BOARD DIAGNOSTIC
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