Hydraulic Control Assembly - Antilock Brakes: Testing and Inspection
HYDRAULIC UNIT CHECKRequired Special Tools:
^ MB991958: Scan Tool (MUT-III Sub Assembly)
^ MB991824: Vehicle Communication Interface (V.C.I.)
^ MB991827: MUT-III USB Cable
^ MB991911: MUT-III Main Harness B
CAUTION:
^ The roller of the braking force tester and the tire 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. Turn the ignition switch to the LOCK (OFF) position.
CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the LOOK (OFF) position before connecting or disconnecting scan tool MB991958.
4. Connect scan tool MB991958 as shown in the illustration.
5. After checking that the shift lever is in neutral, start the engine.
6. Use scan tool MB991958 to force-drive the actuator. For scan tool MB991958, follow the steps below.
1. Select Interactive Diagnosis from the start-up screen.
2. Select System select.
3. Choose ABS from the CHASSIS tab.
4. Select Actuator Test from ABS screen
5. Choose an appropriate item for hydraulic unit check.
NOTE: The ABS system will switch to the scan tool mode and the ABS warning light will illuminate.
NOTE: When the ABS has been interrupted by the fail-safe function, scan tool MB991958 actuator testing cannot be used.
7. 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 reading taken in step 2. The result should be as shown in the diagram above.
8. If the result of inspection is abnormal, repair according to the Diagnosis Table.
9. After inspection, disconnect the scan tool MB991958 immediately after turning the ignition switch to the LOCK (OFF) position.