THEFT DETERRENT SYSTEM (for Sedan) > Security Horn Circuit


DESCRIPTION

When the theft deterrent system is changed from the armed state to the alarm sounding state, the theft warning ECU can sound the security horn. The horn cycles between ON and OFF at intervals of approximately 0.4 seconds.

WIRING DIAGRAM


B121332E01


INSPECTION PROCEDURE

1.PERFORM ACTIVE TEST USING TECHSTREAM (SECURITY HORN)
  1. Connect the Techstream to the DLC3.

  1. Turn the ignition switch to ON.

  1. Turn the tester main switch ON.

  1. Select the item below in the Active Test and then check that the horn operate.

    Theft Warning ECU:

    Item
    Test Details
    Diagnostic Note
    Security Horn
    Security horn ON/OFF
    -

    OK:
    Security horn operates normally.


NG
Go to step 2
OK

PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE 

2.INSPECT FUSE (ECU-B)


    B122728E01
  1. Remove the ECU-B fuse from the engine room R/B.

  1. Measure the resistance.

    Standard resistance:
    Below 1 Ω
  1. Reinstall the ECU-B fuse.



NG
REPLACE FUSE
OK


3.CHECK HARNESS AND CONNECTOR (THEFT WARNING ECU ASSEMBLY- BODY GROUND)


    B121327E10
  1. Disconnect the D26 theft warning ECU connector.

  1. Measure the voltage.

    Standard voltage:
    Tester Connection
    Specified Condition
    D26-13 (+B2) - Body ground
    11 to 14 V
  1. Reconnect the theft warning ECU connector.



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


4.INSPECT SECURITY HORN ASSEMBLY


    B121333E01
  1. Disconnect the A23 security horn connector.

  1. Check the operation of the security horn.

    Standard:
    Measurement Condition
    Specified Condition
    Battery positive (+) → Terminal 1 (B)
    Battery negative (-) → Terminal 2 (L)
    Security horn sounds
  1. Reconnect the security horn connector.



NG
REPLACE SECURITY HORN ASSEMBLY (Click here)
OK


5.CHECK HARNESS AND CONNECTOR (THEFT WARNING ECU ASSEMBLY - SECURITY HORN ASSEMBLY)
  1. Disconnect the D26 theft warning ECU and the A23 security horn connectors.



    B121334E09
  1. Measure the resistance.

    Standard resistance:
    Tester Connection
    Specified Condition
    D26-15 (SH-) - A23-1 (B)
    Below 1 Ω
    A23-2 (L) - Body ground
    Below 1 Ω
    D26-15 (SH-) or A23-1 (B) - Body ground
    10 kΩ or higher
  1. Reconnect the theft warning ECU and the security horn connectors.



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

REPLACE THEFT WARNING ECU ASSEMBLY (Click here)