Last Modified: 07-31-2024 6.11:8.1.0 Doc ID: RM1000000028KBO
Model Year Start: 2023 Model: GR Corolla Prod Date Range: [11/2022 -           ]
Title: THEFT DETERRENT / KEYLESS ENTRY: THEFT DETERRENT SYSTEM: Horn Circuit; 2023 - 2025 MY Corolla Corolla Hatchback Corolla HV GR Corolla [11/2022 -        ]

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 horn 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 2023 - 2025 MY Corolla Corolla HV [09/2022 -        ]; THEFT DETERRENT / KEYLESS ENTRY: SMART KEY SYSTEM (for Start Function, HV Model): REGISTRATION

    for Gasoline Model: Click here 2023 - 2025 MY Corolla Corolla Hatchback GR Corolla [11/2022 -        ]; THEFT DETERRENT / KEYLESS ENTRY: SMART KEY SYSTEM (for Start Function, Gasoline Model): REGISTRATION

  • Inspect the fuses for circuits related to this system before performing the following procedure.

PROCEDURE

1.

INSPECT HORN

(a) Press the horn switch and check if the horn sounds.

Result

Proceed to

Horn sounds

A

Horn does not sound

B
B

GO TO HORN SYSTEM

A

2.

INSPECT POWER DISTRIBUTION BOX ASSEMBLY

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

Click here 2023 - 2025 MY Corolla Corolla Hatchback Corolla HV GR Corolla [11/2022 -        ]; POWER DISTRIBUTION: MAIN BODY ECU: REMOVAL

*a

Component without harness connected

(Power Distribution Box Assembly)

-

-

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

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

8F-10 - MB-23 (HORN)

Always

Below 1 Ω

8D-31 - MB-23 (HORN)

Always

Below 1 Ω
NG

REPLACE POWER DISTRIBUTION BOX ASSEMBLY

OK

3.

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

(a) Remove the HORN relay from the No. 1 engine room relay block and No. 1 junction block assembly.

*1

No. 1 Engine Room Relay Block and No. 1 Junction Block Assembly

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

HORN relay holder terminal 2 - 8F-10

Always

Below 1 Ω

HORN relay holder terminal 2 or 8F-10 - Other terminals and body ground

Always

10 kΩ or higher
OK

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR