Mazda RX-8 Manual page 1487

5. If battery voltage drops below 9 V while vehicle speed is greater than 6 km/h {3.7 mph} , the ABS
HU/CM stores DTC B1318.
6. Precautions during servicing of ABS
The ABS is composed of electrical and mechanical parts. It is necessary to categorize malfunctions as
being either electrical or hydraulic when performing troubleshooting.
a. Malfunctions in electrical system
The ABS HU/CM has an on-board diagnostic function. With this function, any one or a
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combination of the ABS warning light and BRAKE system warning light will illuminate
when there is a problem in the electrical system. Also, past and present malfunctions are
stored in the ABS HU/CM. This function can find malfunctions that do not occur during
periodic inspections. Connect the WDS or equivalent to the DLC-2. Stored malfunctions
will be displayed in the order of occurrence. To find out the causes of ABS malfunctions,
use these on-board diagnostic results.
If a malfunction occurred in the past but is now normal, the cause is likely a temporary
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poor connection of the wiring harness. The ABS HU/CM usually operates normally. Be
careful when searching for the cause of malfunction.
After repair, it is necessary to clear the
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DTC from the ABS HU/CM memory. Also, if the ABS related parts have been replaced,
verify that no DTC is displayed after repairs.
After repairing the ABS wheel-speed sensor or ABS sensor rotor, or after replacing the
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ABS HU/CM, the ABS warning light may not go out (
turned to the ON position. In this case, drive the vehicle at a speed of 10 km/h {6.2 mph}
or more , make sure that ABS warning light goes out, and then clear the DTC.
* The BRAKE system warning light also illuminates when there is any rear wheel
deformation.
When repairing, if the ABS related connectors are disconnected and the ignition switch is
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turned to the ON position, the ABS HU/CM will mistakenly detect a fault and record it as
a malfunction.
To protect the ABS HU/CM, make sure the ignition is off before connecting or
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disconnecting the ABS HU/CM connector.
b. Malfunctions in hydraulic system
Symptoms in a hydraulic system malfunction are similar to those in a conventional brake
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malfunction. However, it is necessary to determine if the malfunction is in an ABS
component or the conventional brake system.
The ABS hydraulic unit contains delicate mechanical parts. If foreign material gets into
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the component, the ABS may fail to operate. Also, it will likely become extremely
difficult to find the location of the malfunction in the event that the brakes operate but the
ABS does not. Make sure foreign material does not enter when servicing the ABS (e.g.
brake fluid replacement, pipe removal).
Vehicle with DSC
1. The ABS warning light and/or BRAKE system warning light and/or DSC indicator light and/or DSC
OFF light illuminate even when the system is normal.
*
) even when the ignition switch is
(w) RX8 - Brakes
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