Horn Circuit: Procedure

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

   Result	Proceed to
   Horns sound	A
   Horns do not sound	B

B → See step   4 

A: Go to next step 

1. Connect Techstream to the DLC3.
2. Turn the ignition switch to the ON position.
3. Turn Techstream main switch on.
4. Select the item below in the Active Test and then check that the horns operate.
   MAIN BODY
   
   

   Tester Display	Test Part	Control Range	Diagnostic Note
   Vehicle Horn	Vehicle horns	ON / OFF	-

   OK

   The vehicle horns sound or stop correctly when operating them through Techstream.

NG → See step   3 

OK → See step   5 

1. Disconnect the 1D instrument panel junction block connector and 2A engine room junction block connector.
   Fig 1: Identifying 1D Instrument Panel Junction Block Connector & 2A Engine Room Junction Block Connector

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Measure the resistance according to the value(s) in the table below.

   Standard resistance

   Tester Connection	Condition	Specified Condition
   1D-11 - 2A-15	Always	Below 1 Ω
   1D-11 - Body ground	Always	10 kΩ or higher

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK → REPLACE MAIN BODY ECU (INSTRUMENT PANEL JUNCTION BLOCK)