Security Horn Circuit [06/2018 - ]: Procedure

1. Connect the Techstream to the DLC3.
2. Turn the engine switch on (IG).
3. Turn the Techstream on.
4. Enter the following menus: Body Electrical / Main Body / Active Test.
5. 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.

   Result

   Proceed to
   OK
   NG

Result: 

OK 

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU). Refer to  REMOVAL [06/2018 - 08/2021]  , or refer to  REMOVAL [08/2021 - 09/2022]  , or refer to  REMOVAL [09/2022 - ] 

Result: 

NG 

See step  2

1. Remove the security horn assembly.

   Refer to REMOVAL [06/2018 - ]

2. Inspect the security horn assembly.

   Refer to INSPECTION [06/2018 - ]

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPLACE SECURITY HORN ASSEMBLY. Refer to  REMOVAL [06/2018 - ] 

Result: 

OK 

See step  3

1. Remove the S-HORN relay from the No. 5 relay block.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *1	S-HORN Relay

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

   Standard Resistance

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

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPLACE S-HORN RELAY 

Result: 

OK 

See step  4

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

   Refer to REMOVAL [06/2018 - 08/2021] , or refer to REMOVAL [08/2021 - 09/2022] , or refer to REMOVAL [09/2022 - ]

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a

   Component without harness connected (Instrument Panel Junction Block Assembly)

   -

   -

2. Disconnect the 3A instrument panel junction block assembly connector.
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

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

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY. Refer to  REMOVAL [06/2018 - 08/2021]  , or refer to  REMOVAL [08/2021 - 09/2022]  , or refer to  REMOVAL [09/2022 - ] 

Result: 

OK 

See step  5

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

   Standard Voltage

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

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *1	No. 5 Relay Block

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  6

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

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   No. 5 relay block S-HORN relay terminal 3 - A16-1	Always	Below 1 Ω
   No. 5 relay block S-HORN relay terminal 3 or A16-1 - Other terminals and body ground	Always	10 kΩ or higher

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *1	No. 5 Relay Block

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  7

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

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   No. 5 relay block S-HORN relay terminal 2 - 3A-20	Always	Below 1 Ω
   No. 5 relay block S-HORN relay terminal 2 or 3A-20 - Other terminals and body ground	Always	10 kΩ or higher

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *1	No. 5 Relay Block

   Result

   Proceed to
   OK
   NG

Result: 

OK 

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU). Refer to  REMOVAL [06/2018 - 08/2021]  , or refer to  REMOVAL [08/2021 - 09/2022]  , or refer to  REMOVAL [09/2022 - ] 

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR