Code No.B120B Security alarm sensor error <Vehicles with security alarm sensor>


caution
  • Before replacing the ECU or sensor, ensure that the power supply circuit, the earth circuit and the communication circuit are normal.
  • When the ETACS-ECU of vehicles without KOS is replaced, the encrypted code of the ignition key needs to be registered to the ETACS-ECU. (If the encrypted code is not registered, the engine cannot be started. Register the encrypted code as described in Immobilizer System - How to Register Key ID .)

DIAGNOSTIC FUNCTION


The security alarm sensor communicates with the ETACS-ECU via the LIN bus line. If the diagnosis code No. B120B is set, the security alarm sensor itself may be defective.
note
  • Diagnosis code No.B120B may be set when the security alarm sensor cover is improperly installed or is removed. Check if the security alarm sensor cover is properly installed.
  • Diagnosis code No.B120B is set when the ultrasonic wave transmission/reception part of the security alarm sensor is covered. Check if the ultrasonic wave transmission/reception part of the security alarm sensor was covered.

PROBABLE CAUSES


Malfunction of the security alarm sensor

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III diagnosis code.


Check if diagnosis code is set to the ETACS-ECU.

Q. Is the diagnosis code set?
Diagnose the ETACS-ECU. Refer to GROUP 54A, Diagnosis .
Go to Step 2.

STEP 2. Security alarm sensor operation check
Ultrasonic wave sensor check

  1. With the windows of the vehicle opened, set the security alarm to the "Ready to be triggered" condition.
  2. Put the arm from the outside to the inside of the vehicle.
  3. Check that the security alarm siren sounds.
Tilt angle sensor check

  1. Set the security alarm to the "Ready to be triggered" condition.
  2. Raise the front wheels or rear wheels.
  3. Check that the security alarm siren sounds.

Q. Is the check result normal?
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).
Go to Step 3.

STEP 3. M.U.T.-III diagnosis code.
Check if diagnosis code No. B120A is set to the ETACS-ECU.

Q. Is diagnosis code No. B120A set?
Perform the troubleshooting of diagnosis code No.B120A. (Refer to .)
NO <The ultrasonic wave sensor is defective, or the ultrasonic wave sensor and the inclination sensor are defective> : Go to Step 4
NO <Only the inclination sensor is defective> : Go to Step 5.

STEP 4. Check the customise function.
Check if the ultrasonic wave sensor of the security alarm senor operates when the sensitivity of the security alarm senor is set to "Level 1".

Q. Is the check result normal?
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).
Go to Step 5

STEP 5. Replace the security alarm sensor temporarily, and check whether the diagnosis code is set.
Check again if the diagnosis code is set to the ETACS-ECU.
(1)Erase the diagnosis code.
(2)Turn the ignition switch from the LOCK (OFF) position to the ON position.
(3)Check if diagnosis code is set.

Q. Is the diagnosis code set?
Replace the ETACS-ECU.
Replace the security alarm sensor.