Toyota Tundra. Manual — part 703

NG: GO TO HORN SYSTEM (See PROBLEM SYMPTOMS TABLE )

OK: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS
TABLE

SECURITY HORN CIRCUIT

DESCRIPTION

When the theft deterrent system is operating, the main body ECU outputs a signal continuously at 0.4 second
intervals, causing the security horn to sound.

WIRING DIAGRAM

Fig. 10: Security Horn - Wiring Diagram
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

INSPECTION PROCEDURE

1. PERFORM ACTIVE TEST BY TECHSTREAM (SECURITY HORN)

a. Operate Techstream according to the steps on the display and select "Active Test".

Techstream

Main Body

TECHSTREAM MAIN BODY REFERENCE CHART

OK: Security horn operates normally.

Tester Display

Test Part Control Range Diagnostic Note

Security Horn Security horn

ON or OFF

-

2009 Toyota Tundra

2009 ACCESSORIES AND EQUIPMENT Theft Deterrent - Tundra

NG: Go to step 2

OK: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS
TABLE

2. INSPECT FUSE (MET-B)

a. Remove the MET-B fuse from the engine room relay block unit B.

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

Standard resistance

FUSE (MET-B)

NG: REPLACE FUSE

OK: Go to Next Step

3. INSPECT SECURITY HORN RELAY

a. Remove the security horn relay from the engine room relay block.

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

Standard resistance

SECURITY HORN RELAY

Fig. 11: Identifying Security Horn Relay
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

NG: REPLACE SECURITY HORN RELAY

Tester Connection Condition Specified Condition

MET-B fuse

Always

Below 1 ohms

Tester

Connection

Condition

Specified

Condition

3 - 5

When battery voltage is not applied between terminals 1
and 2

10 kohms or higher

When battery voltage is applied to terminals 1 and 2

Below 1 ohms

2009 Toyota Tundra

2009 ACCESSORIES AND EQUIPMENT Theft Deterrent - Tundra

OK: Go to Next Step

4. INSPECT SECURITY HORN ASSEMBLY

a. Remove the security horn (see REMOVAL ).

b. Check operation of the horn.

OK

SECURITY HORN ASSEMBLY MEASUREMENT CONNECTION SPECIFIED
CONDITION CHART

Fig. 12: Checking Operation Of Horn
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

NG: REPLACE SECURITY HORN ASSEMBLY (see REMOVAL )

OK: Go to Next Step

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

a. Remove the security horn relay from the engine room relay block.

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

Standard voltage

SECURITY HORN RELAY - BATTERY

Measurement Condition

Specified Condition

Battery positive (+) --> Terminal 1

Battery negative (-) --> Horn bracket

Horn sounds

Tester Connection

Switch

Condition

Specified

Condition

Engine room relay block security horn relay terminal 1 -

Body ground

Ignition switch

ON

11 to 14 V

Engine room relay block security horn relay terminal 5 -

Body ground

Always

2009 Toyota Tundra

2009 ACCESSORIES AND EQUIPMENT Theft Deterrent - Tundra

Fig. 13: Identifying Security Horn Relay
Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

NG: REPAIR OR REPLACE HARNESS OR CONNECTOR

OK: Go to Next Step

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

a. Remove the security horn relay from the engine room relay block.

b. Disconnect the A28 security horn connector.

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

Standard resistance

SECURITY HORN RELAY - SECURITY HORN

Tester Connection

Condition Specified Condition

Engine room relay block security horn relay terminal 3 - A28-1 Always

Below 1 ohms

2009 Toyota Tundra

2009 ACCESSORIES AND EQUIPMENT Theft Deterrent - Tundra