Horn Circuit [06/2018 - ]: Procedure

1. Press the horn switch and check if the horns sound.

   Result

   Result	Proceed to
   Horns sound	A
   Horns do not sound	B

Result: 

B 

GO TO HORN SYSTEM. Refer to  PROBLEM SYMPTOMS TABLE [06/2018 - ] 

Result: 

A 

See step  2

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 3F 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
   3F-27 - MB-28 (HORN)	Always	Below 1 Ω

   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 

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 - ]