THEFT DETERRENT / KEYLESS ENTRY: THEFT DETERRENT SYSTEM: Security Horn Circuit; 2023 - 2025 MY Corolla Corolla Hatchback Corolla HV GR Corolla [11/2022

Last Modified: 05-13-2024	6.11:8.1.0	Doc ID: RM1000000028KBP
Model Year Start: 2023	Model: GR Corolla	Prod Date Range: [11/2022 - ]
Title: THEFT DETERRENT / KEYLESS ENTRY: THEFT DETERRENT SYSTEM: Security Horn Circuit; 2023 - 2025 MY Corolla Corolla Hatchback Corolla HV GR Corolla [11/2022 - ]

Security Horn Circuit

DESCRIPTION

When the theft deterrent system is switched from the armed state to the alarm sounding state, the main body ECU (multiplex network body ECU) transmits a signal to cause the security horn assembly to sound at intervals of 0.4 seconds.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

Before replacing the main body ECU (multiplex network body ECU), refer to Registration.
for HV Model: Click here

for Gasoline Model: Click here
Inspect the fuses for circuits related to this system before performing the following procedure.

PROCEDURE

1.	PERFORM ACTIVE TEST USING GTS

(a) Perform the Active Test according to the display on the GTS.

Body Electrical > Main Body > Active Test

Tester Display	Measurement Item	Control Range	Diagnostic Note
Security Horn	Security horn Assembly	OFF/ON	-

Body Electrical > Main Body > Active Test

Tester Display
Security Horn

OK:

The security horn assembly sounds and stops correctly when operated through the GTS.

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

2.	INSPECT SECURITY HORN ASSEMBLY

Click here

REPLACE SECURITY HORN ASSEMBLY

3.	INSPECT S-HORN RELAY

(a) Remove the S-HORN relay from the No. 3 relay block assembly.

*1	S-HORN Relay

(b) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection	Condition	Specified Condition
3 - 5	Auxiliary battery voltage not applied between terminals 1 and 2	10 kΩ or higher
3 - 5	Auxiliary battery voltage applied between terminals 1 and 2	Below 1 Ω

REPLACE S-HORN RELAY

4.	INSPECT POWER DISTRIBUTION BOX ASSEMBLY

(a) Remove the main body ECU (multiplex network body ECU).

Click here

Component without harness connected

(Power Distribution Box Assembly)

(b) Disconnect the 8D power distribution box assembly connector.

Standard Resistance:

Tester Connection	Condition	Specified Condition
8D-14 - MB-24 (SH)	Always	Below 1 Ω

REPLACE POWER DISTRIBUTION BOX ASSEMBLY

5.	CHECK HARNESS AND CONNECTOR (AUXILIARY BATTERY - S-HORN RELAY)

(a) Measure the voltage according to the value(s) in the table below.

Standard Voltage:

Tester Connection

Condition

Specified Condition

S-HORN relay holder terminal 1 - Body ground

Ignition switch off*1

Always*2

11 to 14 V

S-HORN relay holder terminal 5 - Body ground

Ignition switch off*1

Always*2

11 to 14 V

*1: for HV Model
*2: for Gasoline Model

*1	No. 3 Relay Block Assembly.

REPAIR OR REPLACE HARNESS OR CONNECTOR

6.	CHECK HARNESS AND CONNECTOR (S-HORN RELAY - SECURITY HORN ASSEMBLY)

(a) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection	Condition	Specified Condition
S-HORN relay holder terminal 3 - A16-1	Always	Below 1 Ω
S-HORN relay holder terminal 3 or A16-1 - Other terminals and body ground	Always	10 kΩ or higher

*1	No. 3 Relay Block Assembly.

REPAIR OR REPLACE HARNESS OR CONNECTOR

7.	CHECK HARNESS AND CONNECTOR (S-HORN RELAY - POWER DISTRIBUTION BOX ASSEMBLY)

(a) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection	Condition	Specified Condition
S-HORN relay holder terminal 2 - 8D-14	Always	Below 1 Ω
S-HORN relay holder terminal 2 or 8D-14 - Other terminals and body ground	Always	10 kΩ or higher

*1	No. 3 Relay Block Assembly.

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

REPAIR OR REPLACE HARNESS OR CONNECTOR