HYDRAULIC UNIT CHECK


caution
  • The roller of the braking force tester and the tyre should be dry during testing.
  • When testing the front brakes, apply the parking brake. When testing the rear brakes, stop the front wheels with chocks.
1.Jack up the vehicle. Then support the vehicle with rigid racks at the specified jack-up points or place the front or rear wheels on the rollers of the braking force tester.
2.Release the parking brake, and feel the drag force (drag torque) on each road wheel. When using the braking force tester, take a reading of the brake drag force.
3.
caution To prevent damage to M.U.T.-III, always turn the ignition switch to the "LOOK" (OFF) position before connecting or disconnecting the M.U.T.-III.
Turn the ignition switch to the "LOCK" (OFF) position and set the M.U.T.-III as shown in the illustration.
4.After checking that the selector lever is in neutral, start the engine.
5.Use the M.U.T.-III to force-drive the actuator.
note The ABS system will switch to the M.U.T.-III mode and the ABS warning lamp will illuminate.
note When the ABS has been interrupted by the fail-safe function, the M.U.T.-III actuator testing cannot be used.


6.Turn the wheel by hand and check the change in braking force when the brake pedal is depressed. When using the braking force tester, depress the brake pedal until the braking force is at the following values, and check that the braking force changes to the brake drag force inspected in step 2 when the actuator is force-driven. The result should be as shown in the diagram above.
Front wheel
 785 to 981 N
Rear wheel
 588 to 784 N
7.If the result of inspection is abnormal, repair according to the Diagnosis Table below.
Diagnosis Table
M.U.T.-III Display
 Operation
 Inspection result
 Judgment
 Probable cause
 Remedy
1 FL wheel ABS drive
2 FR wheel ABS drive
3 RL wheel ABS drive
4 RR wheel ABS drive
  • Depress brake pedal to lock wheel.
  • Using the M.U.T.-III, select the wheel to be checked and force the actuator to operate.
  • Turn the selected wheel manually to check the change of brake force.

 Brake force is released for three seconds after wheels have been locked.
 Normal
 -
 -
Wheel does not lock when brake pedal is depressed.
 Abnormal
 Clogged brake line other than hydraulic unit
 Check and clean brake line
Clogged hydraulic circuit in hydraulic unit
 Replace hydraulic unit assembly
Brake force is not released
 Incorrect hydraulic unit brake tube connection
 Connect correctly
Hydraulic unit solenoid valve not functioning correctly
 Replace hydraulic unit assembly
8.After inspection, disconnect the M.U.T.-III immediately after turning the ignition switch to the "LOCK" (OFF) position.