Last Modified: 05-13-2024 6.11:8.1.0 Doc ID: RM100000001HAPN
Model Year Start: 2020 Model: Corolla Prod Date Range: [01/2019 - 09/2022]
Title: THEFT DETERRENT / KEYLESS ENTRY: THEFT DETERRENT SYSTEM (for HV Model): Security Horn Circuit; 2020 - 2022 MY Corolla Corolla HV [01/2019 - 09/2022]

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.

    Click here 2020 MY Corolla Corolla HV [01/2019 - 04/2020]; THEFT DETERRENT / KEYLESS ENTRY: SMART KEY SYSTEM (for Start Function, HV Model): REGISTRATION 2021 - 2022 MY Corolla Corolla HV [04/2020 - 09/2022]; THEFT DETERRENT / KEYLESS ENTRY: SMART KEY SYSTEM (for Start Function, HV Model): REGISTRATION

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

PROCEDURE

1.

PERFORM ACTIVE TEST USING TECHSTREAM (SECURITY HORN)

(a) Connect the Techstream to the DLC3.

(b) Turn the power switch on (IG).

(c) Turn the Techstream on.

(d) Enter the following menus: Body Electrical / Main Body / Active Test.

(e) Perform the Active Test according to the display on the Techstream.

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 Techstream.

OK

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) 2020 MY Corolla Corolla Hatchback Corolla HV GR Corolla [01/2019 - 03/2019]; POWER DISTRIBUTION: MAIN BODY ECU: REMOVAL 2020 - 2022 MY Corolla Corolla Hatchback Corolla HV GR Corolla [03/2019 - 09/2022]; POWER DISTRIBUTION: MAIN BODY ECU: REMOVAL

NG

2.

INSPECT SECURITY HORN ASSEMBLY

(a) Remove the security horn assembly.

Click here 2020 - 2025 MY Corolla Corolla HV [01/2019 -        ]; THEFT DETERRENT / KEYLESS ENTRY: SECURITY HORN ASSEMBLY (for HV Model): REMOVAL

(b) Inspect the security horn assembly.

Click here 2020 - 2025 MY Corolla Corolla HV [01/2019 -        ]; THEFT DETERRENT / KEYLESS ENTRY: SECURITY HORN ASSEMBLY (for HV Model): INSPECTION

NG

REPLACE SECURITY HORN ASSEMBLY

OK

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
NG

REPLACE S-HORN RELAY
OK

4.

INSPECT INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY

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

Click here 2020 MY Corolla Corolla Hatchback Corolla HV GR Corolla [01/2019 - 03/2019]; POWER DISTRIBUTION: MAIN BODY ECU: REMOVAL 2020 - 2022 MY Corolla Corolla Hatchback Corolla HV GR Corolla [03/2019 - 09/2022]; POWER DISTRIBUTION: MAIN BODY ECU: REMOVAL

*a

Component without harness connected

(Instrument Panel Junction Block Assembly)

-

-

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

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

4B-26 - MB-29 (SH)

Always

Below 1 Ω
NG

REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY 2020 MY Corolla Corolla Hatchback Corolla HV GR Corolla [01/2019 - 03/2019]; POWER DISTRIBUTION: MAIN BODY ECU: REMOVAL 2020 - 2022 MY Corolla Corolla Hatchback Corolla HV GR Corolla [03/2019 - 09/2022]; POWER DISTRIBUTION: MAIN BODY ECU: REMOVAL

OK

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

Power switch off

11 to 14 V

No. 3 relay block assembly S-HORN relay terminal 5 - Body ground

Power switch off

11 to 14 V

*1

No. 3 Relay Block Assembly
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

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
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

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
OK

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) 2020 MY Corolla Corolla Hatchback Corolla HV GR Corolla [01/2019 - 03/2019]; POWER DISTRIBUTION: MAIN BODY ECU: REMOVAL 2020 - 2022 MY Corolla Corolla Hatchback Corolla HV GR Corolla [03/2019 - 09/2022]; POWER DISTRIBUTION: MAIN BODY ECU: REMOVAL

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR