INSPECTION PROCEDURE 4: HBB buzzer does not stop sounding.








note This diagnosis procedure is limited to cases where communication with the M.U.T.-III is possible (ASTC-ECU power supply is normal) and no diagnosis code sets.

OPERATION



  • The ASTC-ECU and the transfer-ECU controls the buzzer by turning the power transistor in the ECU ON and OFF.
  • The ASTC-ECU outputs the buzzer-sounding signal when an abnormality occurs on the hydraulic brake booster (At the same time, the ASTC-ECU turns on the brake warning light).

COMMENT ON TROUBLE SYMPTOM



PROBABLE CAUSES



  • Damaged wiring harness or connector
  • Malfunction of the ASTC-ECU
  • Malfunction of the buzzer

DIAGNOSIS

STEP 1. Check the buzzer circuit at D-232 ASTC-ECU connector.
(1)Disconnect D-232 ASTC-ECU connector.
(2)Turn the ignition switch to the "ON" position.
(3)Check if the HBB buzzer keeps on sounding.

Q. Does the buzzer still keep on sounding?
Go to Step 2.
Replace the ASTC-ECU (Refer to GROUP 35C, ASTC-ECU ). Then go to Step 4.

STEP 2. Check D-102 buzzer connector and D-232 ASTC-ECU connector for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q. Are the connectors and terminals in good condition?
Go to Step 3.
Repair the faulty connector or terminal. Then go to Step 4.

STEP 3. Check the harness wires between D-102 buzzer connector terminal No.2 and D-232 ASTC-ECU connector terminal No.54.

Q. Is the check result normal?
Replace the buzzer (Refer to ). Then go to Step 4.
Repair or replace it. Then go to Step 4.

STEP 4. Retest the system.
caution Before connecting or disconnecting the M.U.T.-III, turn the ignition switch to the "LOCK" (OFF) position.
(1)Connect M.U.T.-III to the diagnosis connector.
(2)Turn the ignition switch to the "ON" position.
(3)Using M.U.T.-III, check actuator test and sound the buzzer.

Q. Does the buzzer sound for three seconds and then stop?

The procedure is complete.
Start over at Step 1.