Toyota CH-R Service Manual: Security Horn Circuit

Toyota CH-R Service Manual / Theft Deterrent / Keyless Entry / Theft Deterrent System / 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*1.
Click here

*1: w/ Smart Key System
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 ignition switch to 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.

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

2.	INSPECT SECURITY HORN ASSEMBLY

(a) Remove the security horn assembly.

Click here

(b) Inspect the security horn assembly.

Click here

REPLACE SECURITY HORN ASSEMBLY

3.	INSPECT S-HORN RELAY

(a) Remove the S-HORN relay from the No. 4 relay block assembly.

(b) Inspect the S-HORN relay.

Click here

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 3A instrument panel junction block assembly connector.

Standard Resistance:

Tester Connection	Condition	Specified Condition
3A-20 - MB-29 (SH)	Always	Below 1 Ω

REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY

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

(a) Remove the S-HORN relay from the No. 4 relay block assembly.

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
No. 4 relay block assembly S-HORN relay terminal 1 - Body ground	Always	11 to 14 V
No. 4 relay block assembly S-HORN relay terminal 5 - Body ground	Always	11 to 14 V

*1	No. 4 Relay Block Assembly

REPAIR OR REPLACE HARNESS OR CONNECTOR

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

(a) Remove the S-HORN relay from the No. 4 relay block assembly.

(b) Disconnect the A15 security horn assembly connector.

Standard Resistance:

Tester Connection	Condition	Specified Condition
No. 4 relay block assembly S-HORN relay terminal 3 - A15-1	Always	Below 1 Ω
No. 4 relay block assembly S-HORN relay terminal 3 or A15-1 - Body ground	Always	10 kΩ or higher

*1	No. 4 Relay Block Assembly

REPAIR OR REPLACE HARNESS OR CONNECTOR

7.	CHECK HARNESS AND CONNECTOR (S-HORN RELAY - INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY)

(a) Remove the S-HORN relay from the No. 4 relay block assembly.

(b) Disconnect the 3A instrument panel junction block assembly connector.

Standard Resistance:

Tester Connection	Condition	Specified Condition
No. 4 relay block assembly S-HORN relay terminal 2 - 3A-20	Always	Below 1 Ω
No. 4 relay block assembly S-HORN relay terminal 2 or 3A-20 - Body ground	Always	10 kΩ or higher

*1	No. 4 Relay Block Assembly

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

REPAIR OR REPLACE HARNESS OR CONNECTOR

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 horns to s ...

Improper Operation

DESCRIPTION When the theft deterrent system operates by itself, it could be due to something such as a short circuit in the courtesy light switch of any of the doors or the hood causing a signal ...

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