Hydraulic Unit
- Jack up vehicle and support. Place wheels to be tested on rollers of braking force tester. Ensure roller of the braking force tester and vehicle tire are dry during testing.
- Release parking brake and feel drag force (drag torque) on each road wheel. When using braking force tester, take a reading of brake drag force on each road wheel.
- Turn ignition key to LOCK position and connect MUT-II tester or scan tool to Data Link Connector (DLC).
- With vehicle transmission in NEUTRAL position, start engine. At this time ABS system will switch to scan tool mode and ABS warning light will illuminate (If ABS has been interrupted by fail-safe function, scan tool actuator testing cannot be used).
- Use MUT-II tester or scan tool to force drive the actuator.
- Turn wheel by hand and check change in braking force when brake pedal is depressed. When using the brake force tester, depress brake pedal until braking force is at the following values. See BRAKE PEDAL FORCE INDEX table. Check to be sure that braking force changes to brake force inspected in step 2 when actuator is force driven.
- If result of inspection is abnormal, correct according to information in next step.
- Perform the following diagnostic procedure:
- Depress brake pedal to lock wheel.
- Using MUT-II tester or scan tool, select wheel to be checked and force actuator to operate.
- Turn selected wheel manually to check change of brake force.
In a normal condition brake force will be released for 2 seconds after locking. If condition is abnormal the wheel may not lock when brake pedal is depressed or brake force will not be released and wheel will stay locked. If wheel does not lock when brake pedal is depressed, probable cause could be a clogged brake line or circuit inside or outside the hydraulic unit. See Fig 1 . To repair, check and clean brake line or replace hydraulic unit. See ABS ELECTRONIC CONTROL & HYDRAULIC UNIT under REMOVAL & INSTALLATION. If brake force is not released, probable cause is an incorrect brake line connection or hydraulic unit solenoid valve is not functioning correctly. To repair, connect brake line to proper connection on hydraulic unit. See Fig 1 . If hydraulic unit solenoid is not functioning properly, replace hydraulic unit.
BRAKE PEDAL FORCE INDEXApplication Lbs. (N.m) Front Wheel 176-220 (785-981) Rear Wheel 66-110 (294-490) - After inspection, disconnect MUT-II tester or scan tool immediately after turning ignition switch to LOCK position.