ABS HU/CM SYSTEM INSPECTION

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ABS Hydraulic Unit On-vehicle Inspection


Preparation

1.  Verify that the battery is fully charged.

2.  Turn the ignition switch or engine switch to the ON position and verify that the ABS warning light goes out after approx. 3.0 s.

3.  Turn the ignition switch or engine switch off.

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

5.  Shift to neutral.

6.  Release the parking brake.

7.  Verify that all four wheels rotate.

8.  Rotate the inspected wheels by hand and verify 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.  Perform “Preparation”.

2.  Connect the M-MDS to the DLC-2 connector.

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3.  Set up an active command mode inspection according to the combination of commands below.

Operation condition

Command name

Command

transmission type

PMP_MOTOR

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.
Caution
•  When operating the solenoid valve and pump motor using the active command mode, make sure to keep the operation time within 10 s to prevent damaging the ABS HU/CM.
Note
•  When working with two people, one should press on the brake pedal, the other should attempt to rotate the wheel being inspected.

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

5.  Performing the inspection above determines the following:

•  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.
•  Malfunction of ABS HU/CM input system wiring harnesses and parts
•  Extremely small leakage in the ABS HU/CM internal hydraulic system
•  Intermittent malfunction of the above items