ABS HU/CM SYSTEM INSPECTION

BME041343780201

System Inspection

Preparation

1. Verify that the battery is fully charged. With the ignition switch on, verify that the ABS and BRAKE system warning lights goes out after 3 seconds.

Note
• If the lights stays on after 3 seconds, the ABS HU/CM detects a failure. Follow the troubleshooting procedures.

2. Turn the ignition switch off.

3. On level ground, jack up the vehicle and support it evenly on safety stands. Shift the transaxle to N position.

4. Release the parking brake.

5. Rotate the wheels by hand, and inspect for brake drag.

Using the SSTs

1. Perform the "Preparation".

2. Connect the WDS or equivalent to DLC-2.

3. Set up an active command mode inspection according to the combination of commands below. (Refer to ABS, ABS/TCS ON-BOARD DIAGNOSIS.)

OPERATION

COMMAND NAME

COMMAND TYPE

PMP MOTOR

RF OUTLET

RF INLET

VPWRRLY

Pressure retention
OFF
OFF
ON
ON
Manual
Pressure reduction
ON
ON
ON
ON

The chart above shows an example of a right wheel inspection.

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

5. When pressure is being maintained, and click sound indicating the solenoid is operating comes from the ABS HU/CM, confirm that the wheel does not rotate. When pressure is being reduced, and click sound indicating the solenoid is operating comes from the ABS HU/CM, confirm that the wheel rotates, even though the brake pedal is being depressed.

Note
• When working with two people, one should press on the brake pedal, the other should attempt to rotate the wheel being inspected.
• To protect the ABS HU/CM, the solenoid valve used for simulations and the ABS motor stay on for 10 seconds each time they are switched on.
• Performing the inspections above determines the following.
- The ABS HU/CM brake lines are normal.
- The ABS HU/CM hydraulic system is not significantly abnormal.
- The ABS HU/CM wiring is normal.
• However, the following items cannot be checked.
- ABS HU/CM input system harness and parts
- Extremely small leaks in the ABS HU/CM internal hydraulic system
- Unusual intermittent occurrences in the above items 1 through 3

Without using the SSTs

1. Perform the "Preparation".

2. Use a jumper wire to short terminal TBS of the DLC to body GND.

Caution
• Connecting the wrong data link connector (DLC) terminals may possibly cause a malfunction. Carefully connect the specified terminals only.

3. Depress the brake pedal, and have an assistant verify that the right front wheel does not turn.

4. With the brake pedal still depressed, turn the ignition switch on and verify that the brake is released momentarily (approx. 0.5 seconds) and that the wheel turns when pressure-reduction operates.

5. Inspect the operation of the remaining wheels in order: right front, left front, right rear, left rear.

• Replace the ABS HU/CM if wheels do not rotate.
• Inspect brake piping to ABS HU/CM if operation of the remaining wheel order is not within specified.
Note
• If Steps 4 and 5 show correct operation, the following systems are okay:
- Brake piping to ABS HU/CM
- Braking system, including ABS HU/CM
- Electrical system in ABS HU/CM (solenoid, ABS motor, etc.)
• The following are not inspected with above steps:
- Input system and harness of ABS HU/CM
- Intermittent failure
- Fluid leakage from brake including the ABS HU/CM and master cylinder

6. Turn the ignition switch off and remove the jumper wire.