Inspection Procedure 9: ABS Operate Too Frequently

INSPECTION PROCEDURE 9: ABS operate too frequently.

COMMENTS ON TROUBLE SYMPTOM
^ Although the cause of the trouble cannot be clearly resolved since it depends on the running status and road surface condition, the malfunction of the hydraulic circuit may occur if any diagnosis code is not detected.
^ If wheels and tires other than the ones with genuine specified size are mounted, the ABS may be activated prematurely.
^ If a non-genuine braking device or non-genuine impact reduction device is mounted, the ABS may be activated prematurely.

PROBABLE CAUSES
^ Mounting of wheels and tires other than with genuine specified size
^ Tire pressure abnormality
^ Tire wear and deterioration
^ Mounting of non-genuine braking device or impact reduction device
^ Wheel alignment abnormality
^ Malfunction of brake related parts
^ ABS-ECU malfunction
^ Malfunction of hydraulic circuit
^ External radio wave noise interference

DIAGNOSIS PROCEDURE

STEP 1. Check the wheels and the tires.
Carry out the following check.
^ Size check of wheels and tires
^ Tire wear and deterioration statuses
^ Check the tire pressure.

NOTE: For the tire pressure, refer to the tire pressure label attached to the lower section of driver's side door striker.

Q: Is the check result normal?
YES: Go to Step 2.
NO: Correct the wheels and tires in good condition. Then go to Step 9.

STEP 2. DTC check
Use scan tool to check the DTC for the ABS system.

Q: Is the check result normal?
YES: Go to Step 3.
NO: Carry out the diagnosis for the DTC. Then go to Step 9.

STEP 3. Check of brake system related components other than hydraulic unit (integrated with ABS-ECU)
At the same time with the following checks, also check that no parts other than the genuine parts are mounted.
^ Brake pad check.
^ Brake disc runout check.
^ Brake drag force check.

Q: Is the check result normal?
YES: Go to Step 4.
NO: Repair or replace the part(s) having damage or other problems. Then go to Step 9.

STEP 4. Wheel alignment check
At the same time with the following checks, also check that no parts other than the genuine parts are mounted.
^ Front wheel alignment check.
^ Rear wheel alignment check.

Q: Is the check result normal?
YES: Go to Step 5.
NO: Repair or replace the part(s) having damage or other problems. Then go to Step 9.

STEP 5. M.U.T.-III data list
Check the following service data.
^ Item No. 01: FL wheel speed sensor
^ Item No.02: FR wheel speed sensor
^ Item No.03: RL wheel speed sensor
^ Item No.04: RR wheel speed sensor

Q: Is the check result normal?
YES: Go to Step 7.
NO: Go to Step 6.

STEP 6. Wheel speed sensor check
Check that no non-genuine electronic device or no wiring harness of other than genuine electronic device is mounted near the wheel speed sensor (at wheel speed detection section and wiring harness section).

Q: Is the check result normal?
YES: Go to Step 7.
NO: Remove the non-genuine electronic device or the wiring harness of non-genuine electronic device. Then go to Step 9.

STEP 7. Hydraulic unit check
Carry out the following actuator tests, and check if they work normally.
^ Item No. 01: FL wheel ABS
^ Item No.02: FR wheel ABS
^ Item No.03: RL wheel ABS
^ Item No.04: RR wheel ABS

Q: Is the check result normal?
YES: Go to Step 8.
NO: Replace the hydraulic unit (integrated with ABS-ECU). Then go to Step 9.

STEP 8. ABS operation check

Q: Is the check result normal?
YES: Intermittent malfunction.
NO: Replace the hydraulic unit (integrated with ABS-ECU). Then go to Step 9.

STEP 9. ABS operation check

Q: Is the check result normal?
YES: The procedure is complete.
NO: Return to Step 1.