THEFT DETERRENT / KEYLESS ENTRY: THEFT DETERRENT SYSTEM (for TMMMS Made): Security Horn Circuit; 2023 MY Corolla Corolla Hatchback Corolla HV GR Corolla [09/2022

Last Modified: 05-13-2024	6.11:8.1.0	Doc ID: RM1000000026A7Q
Model Year Start: 2023	Model: GR Corolla	Prod Date Range: [09/2022 - 11/2022]
Title: THEFT DETERRENT / KEYLESS ENTRY: THEFT DETERRENT SYSTEM (for TMMMS Made): Security Horn Circuit; 2023 MY Corolla Corolla Hatchback Corolla HV GR Corolla [09/2022 - 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
- *: w/ Smart Key System
Inspect the fuses for circuits related to this system before performing the following procedure.

PROCEDURE

1.	PERFORM ACTIVE TEST USING GTS (SECURITY HORN)

(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

(a) 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 INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY

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

Click here

Component without harness connected

(Instrument Panel Junction Block Assembly)

(b) Disconnect the 4B instrument panel junction block assembly connector.

Standard Resistance:

Tester Connection	Condition	Specified Condition
4B-26 - MB-29 (SH)	Always	Below 1 Ω

REPLACE INSTRUMENT PANEL JUNCTION BLOCK 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
No. 3 relay block assembly S-HORN relay terminal 1 - Body ground	Always	11 to 14 V
No. 3 relay block assembly S-HORN relay terminal 5 - Body ground	Always	11 to 14 V

*1	No. 3 Relay Block Assembly

REPAIR OR REPLACE HARNESS OR CONNECTOR

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

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
No. 3 relay block assembly S-HORN relay terminal 3 - A16-1	Always	Below 1 Ω
No. 3 relay block assembly S-HORN relay 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 - INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY AND BODY GROUND)

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
No. 3 relay block assembly S-HORN relay terminal 2 - 4B-26	Always	Below 1 Ω
No. 3 relay block assembly S-HORN relay terminal 2 or 4B-26 - 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