Toyota Venza: Security Horn Circuit

Toyota Venza Service Manual / Theft Deterrent / Keyless Entry / Theft Deterrent System(w/ Smart Key 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 (driver side junction block assembly) controls the security horn.

WIRING DIAGRAM

PROCEDURE

1.	PERFORM ACTIVE TEST USING TECHSTREAM

(a) Connect the Techstream to the DLC3.

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

(d) Select the item below in the Active Test and then check that the security horn assembly operates.

Body

Tester Display	Test Part	Control Range	Diagnostic Note
Security Horn	Security horn	ON/OFF	-

OK:

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

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

2.	INSPECT SECURITY HORN ASSEMBLY

(a) Remove the security horn assembly (See page ).

(b) Check the operation of the security horn assembly.

OK:

Measurement Condition	Specified Condition
Battery positive (+) → Terminal 1	Horn sounds
Battery negative (-) → Horn body	Horn sounds

REPLACE SECURITY HORN ASSEMBLY

3.	INSPECT SEC HORN RELAY

(a) Remove the SEC HORN relay from the engine room relay block.

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

Standard Resistance:

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

REPLACE SEC HORN RELAY

4.	CHECK HARNESS AND CONNECTOR (SEC HORN RELAY POWER SOURCE)

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
Engine room relay block SEC HORN relay terminal 1 - Body ground	Always	Below 1 V

Text in Illustration

*1	Engine Room Relay Block
*2	SEC HORN Relay Terminal

REPAIR OR REPLACE HARNESS OR CONNECTOR

5.	CHECK HARNESS AND CONNECTOR (SEC HORN RELAY - MAIN BODY ECU)

(a) Disconnect the D51 main body ECU (driver side junction block assembly) connector.

(b) Measure the resistance on the relay block side according to the value(s) in the table below.

Standard Resistance:

Tester Connection	Condition	Specified Condition
Engine room relay block SEC HORN relay terminal 1 - D51-6 (SH)	Always	Below 1 Ω
Engine room relay block SEC HORN relay terminal 1 - Body ground	Always	10 kΩ or higher

Text in Illustration

Engine Room Relay Block

SEC HORN Relay Terminal

Front view of wire harness connector

(to Main Body ECU (Driver Side Junction Block Assembly))

REPAIR OR REPLACE HARNESS OR CONNECTOR

6.	CHECK HARNESS AND CONNECTOR (SEC HORN RELAY POWER SOURCE)

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
Engine room relay block SEC HORN relay terminal 3 - Body ground	Always	Below 1 V

Text in Illustration

*1	Engine Room Relay Block
*2	SEC HORN Relay Terminal

REPAIR OR REPLACE HARNESS OR CONNECTOR

7.	CHECK HARNESS AND CONNECTOR (SEC HORN RELAY - SECURITY HORN ASSEMBLY)

(a) Disconnect the A23 security horn assembly connector.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
Engine room relay block SEC HORN relay terminal 5 - A23-1	Always	Below 1 Ω
Engine room relay block SEC HORN relay terminal 5 - Body ground	Always	10 kΩ or higher

Text in Illustration

Engine Room Relay Block

SEC HORN Relay Terminal

Front view of wire harness connector

(to Security Horn Assembly)

REPLACE MAIN BODY ECU (DRIVER SIDE JUNCTION BLOCK ASSEMBLY)

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 (driver side junction block assembly) transmits a signal to cause the h ...

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