ABS SYSTEM INSPECTION

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ABS Hydraulic Unit On-vehicle Inspection


Preparation

1.  Verify that the battery is completely charged.

2.  Turn the ignition switch to the ON position and verify that the ABS warning light illuminates and turns off after approx. 3.0 s.

3.  Turn the ignition switch to the LOCK position.

4.  Jack up the vehicle and support it evenly on safety stands.

5.  Shift to neutral.

6.  Release the parking brake.

7.  Verify that the 4 wheels rotate.

8.  Rotate the inspected wheels by hand and verify that there is no brake drag.

•  If there is any brake drag, perform regular brake inspection.
•  If there is no brake drag, perform ABS HU/CM operation inspection.


Operation inspection

1.  Make preparations.

2.  Connect the M-MDS to the DLC-2.

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3.  Set up an active command mode inspection according to the combination of commands below. (See ON-BOARD DIAGNOSIS [ABS].)

Operation condition

Command name

Command

Transmission type

PMP_MTR

V_RF_OTL

V_RF_INL
Brake pressure retention
Off
Off
On
Manual
Brake pressure reduction
On
On
On

The chart above shows an example of a right front wheel inspection.
Note
•  One technician depresses the brake pedal, while the other does the inspection by applying force to the vehicle tire in the direction of rotation.

4.  Send the command while depressing the brake pedal and attempting to rotate the wheel being inspected.

5.  ABS HU verify that the solenoid activation sound is produced from CM, the vehicle wheels do not rotate under brake pressure retention conditions, and the wheels rotate under brake pressure reduction conditions.

•  With the above inspection, verify that the following items are normal.
―  The ABS HU/CM brake lines are normal.
―  The ABS HU/CM hydraulic system is not significantly abnormal (including inside ABS HU/CM).
―  The ABS HU/CM internal electrical parts (solenoid, motor and other parts) are normal.
―  The ABS HU/CM output system wiring harnesses (solenoid valve, relay system) are normal.
•  However, the following items cannot be verified.
―  Part malfunction in input related wiring harness of ABS HU/CM and parts
―  Extremely small leaks in the ABS HU/CM internal hydraulic system
―  Intermittent malfunction of the above items